[CLEANUP] proxy: rename a few proxy states (PR_STIDLE and PR_STRUN)

Those states have been replaced with PR_STFULL and PR_STREADY respectively,
as it is what matches them the best now. Also, two occurrences of PR_STIDLE
in peers.c have been removed as this did not provide any form of error recovery
anyway.
diff --git a/src/dumpstats.c b/src/dumpstats.c
index f3619a7..3ef2278 100644
--- a/src/dumpstats.c
+++ b/src/dumpstats.c
@@ -2050,8 +2050,8 @@
 				     "",
 				     U2H0(px->fe_counters.denied_req), U2H1(px->fe_counters.denied_resp),
 				     U2H2(px->fe_counters.failed_req),
-				     px->state == PR_STRUN ? "OPEN" :
-				     px->state == PR_STIDLE ? "FULL" : "STOP");
+				     px->state == PR_STREADY ? "OPEN" :
+				     px->state == PR_STFULL ? "FULL" : "STOP");
 			} else {
 				chunk_printf(&msg,
 				     /* pxid, name, queue cur, queue max, */
@@ -2081,8 +2081,8 @@
 				     px->fe_counters.bytes_in, px->fe_counters.bytes_out,
 				     px->fe_counters.denied_req, px->fe_counters.denied_resp,
 				     px->fe_counters.failed_req,
-				     px->state == PR_STRUN ? "OPEN" :
-				     px->state == PR_STIDLE ? "FULL" : "STOP",
+				     px->state == PR_STREADY ? "OPEN" :
+				     px->state == PR_STFULL ? "FULL" : "STOP",
 				     relative_pid, px->uuid, STATS_TYPE_FE,
 				     read_freq_ctr(&px->fe_sess_per_sec),
 				     px->fe_sps_lim, px->fe_counters.sps_max);