CLEANUP: contrib/prometheus-exporter: typo fixes for ssl reuse metric

A typo I identified while having a look to our metric inventory.
(s/frontent/frontend)

(cherry picked from commit 1e3697635292b0f194171958a26766ae3e8d8453)
[wt: actually it fixes a real issue as the typo was user-visible]
Signed-off-by: Willy Tarreau <w@1wt.eu>
(cherry picked from commit 2e50e5d1ea9b3af6cb87c52f23c6fc7b0e140b37)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
(cherry picked from commit 152535c9816f5a4b73509bf557b316c4b61a2805)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>
2 files changed