CLEANUP: contrib/prometheus-exporter: align and reorder fields

- align safe_idle_connections_current field
  fix minor typo added in commit
  37286a5ac595069a491c3e8a7a7e4faf3d9ea8ad ("MEDIUM:
  contrib/prometheus-exporter: Rework matrices defining Promex metrics")
- reorder info fields to be able to compare them easily
- add missing ignored info fields as comment

Signed-off-by: William Dauchy <wdauchy@gmail.com>
diff --git a/contrib/prometheus-exporter/service-prometheus.c b/contrib/prometheus-exporter/service-prometheus.c
index bfcc126..8674cf3 100644
--- a/contrib/prometheus-exporter/service-prometheus.c
+++ b/contrib/prometheus-exporter/service-prometheus.c
@@ -108,7 +108,6 @@
 	//[INF_NAME]                           ignored
 	//[INF_VERSION],                       ignored
 	//[INF_RELEASE_DATE]                   ignored
-	[INF_BUILD_INFO]                     = { .n = IST("build_info"),                    .type = PROMEX_MT_GAUGE,   .flags = PROMEX_FL_INFO_METRIC },
 	[INF_NBTHREAD]                       = { .n = IST("nbthread"),                      .type = PROMEX_MT_GAUGE,   .flags = PROMEX_FL_INFO_METRIC },
 	[INF_NBPROC]                         = { .n = IST("nbproc"),                        .type = PROMEX_MT_GAUGE,   .flags = PROMEX_FL_INFO_METRIC },
 	[INF_PROCESS_NUM]                    = { .n = IST("relative_process_id"),           .type = PROMEX_MT_GAUGE,   .flags = PROMEX_FL_INFO_METRIC },
@@ -116,8 +115,11 @@
 	//[INF_UPTIME]                         ignored
 	[INF_UPTIME_SEC]                     = { .n = IST("uptime_seconds"),                .type = PROMEX_MT_GAUGE,   .flags = PROMEX_FL_INFO_METRIC },
 	[INF_START_TIME_SEC]                 = { .n = IST("start_time_seconds"),            .type = PROMEX_MT_GAUGE,   .flags = PROMEX_FL_INFO_METRIC },
+	//[INF_MEMMAX_MB]                      ignored
 	[INF_MEMMAX_BYTES]                   = { .n = IST("max_memory_bytes"),              .type = PROMEX_MT_GAUGE,   .flags = PROMEX_FL_INFO_METRIC },
+	//[INF_POOL_ALLOC_MB]                  ignored
 	[INF_POOL_ALLOC_BYTES]               = { .n = IST("pool_allocated_bytes"),          .type = PROMEX_MT_GAUGE,   .flags = PROMEX_FL_INFO_METRIC },
+	//[INF_POOL_USED_MB]                   ignored
 	[INF_POOL_USED_BYTES]                = { .n = IST("pool_used_bytes"),               .type = PROMEX_MT_GAUGE,   .flags = PROMEX_FL_INFO_METRIC },
 	[INF_POOL_FAILED]                    = { .n = IST("pool_failures_total"),           .type = PROMEX_MT_COUNTER, .flags = PROMEX_FL_INFO_METRIC },
 	[INF_ULIMIT_N]                       = { .n = IST("max_fds"),                       .type = PROMEX_MT_GAUGE,   .flags = PROMEX_FL_INFO_METRIC },
@@ -173,6 +175,7 @@
 	[INF_BYTES_OUT_RATE]                 = { .n = IST("bytes_out_rate"),                .type = PROMEX_MT_GAUGE,   .flags = PROMEX_FL_INFO_METRIC },
 	//[INF_DEBUG_COMMANDS_ISSUED]          ignored
 	[INF_CUM_LOG_MSGS]                   = { .n = IST("recv_logs_total"),               .type = PROMEX_MT_COUNTER, .flags = PROMEX_FL_INFO_METRIC },
+	[INF_BUILD_INFO]                     = { .n = IST("build_info"),                    .type = PROMEX_MT_GAUGE,   .flags = PROMEX_FL_INFO_METRIC },
 };
 
 /* frontend/backend/server fields */
@@ -273,7 +276,7 @@
 	[ST_F_TT_MAX]         = { .n = IST("max_total_time_seconds"),           .type = PROMEX_MT_GAUGE,    .flags = (                         PROMEX_FL_BACK_METRIC | PROMEX_FL_SRV_METRIC) },
 	[ST_F_EINT]           = { .n = IST("internal_errors_total"),            .type = PROMEX_MT_COUNTER,  .flags = (PROMEX_FL_FRONT_METRIC | PROMEX_FL_BACK_METRIC | PROMEX_FL_SRV_METRIC) },
 	[ST_F_IDLE_CONN_CUR]  = { .n = IST("unsafe_idle_connections_current"),  .type = PROMEX_MT_GAUGE,    .flags = (                                                 PROMEX_FL_SRV_METRIC) },
-	[ST_F_SAFE_CONN_CUR]=   { .n = IST("safe_idle_connections_current"),    .type = PROMEX_MT_GAUGE,    .flags = (                                                 PROMEX_FL_SRV_METRIC) },
+	[ST_F_SAFE_CONN_CUR]  = { .n = IST("safe_idle_connections_current"),    .type = PROMEX_MT_GAUGE,    .flags = (                                                 PROMEX_FL_SRV_METRIC) },
 	[ST_F_USED_CONN_CUR]  = { .n = IST("used_connections_current"),         .type = PROMEX_MT_GAUGE,    .flags = (                                                 PROMEX_FL_SRV_METRIC) },
 	[ST_F_NEED_CONN_EST]  = { .n = IST("need_connections_current"),         .type = PROMEX_MT_GAUGE,    .flags = (                                                 PROMEX_FL_SRV_METRIC) },
 	[ST_F_UWEIGHT]        = { .n = IST("uweight"),                          .type = PROMEX_MT_GAUGE,    .flags = (                         PROMEX_FL_BACK_METRIC | PROMEX_FL_SRV_METRIC) },