Revert "BUG/MINOR: resolvers: Only renew TTL for SRV records with an additional record"

Revert "BUG/MINOR: resolvers: Only renew TTL for SRV records with an additional record"

This reverts commit a331a1e8eb2ad4750711a477ca3e22d940495faf.

This commit fixes a real bug, but it also reveals some hidden bugs, mostly
because of some design issues. Thus, in itself, it create more problem than
it solves. So revert it for now. All known bugs will be addressed in next
commits.

This patch should be backported as far as 2.2.

(cherry picked from commit 5037c06d91e0ed748932fcfaae11eeadf5949957)
Signed-off-by: Christopher Faulet <cfaulet@haproxy.com>