BUG/MEDIUM: check: reuse srv proto only if using same mode

Only reuse the mux from server if the check is using the same mode.
For example, this prevents a tcp-check on a h2 server to select the h2
multiplexer instead of passthrough.

This bug was introduced by the following commit :
BUG/MEDIUM: checks: Use the mux protocol specified on the server line
It must be backported up to 2.2.

Fixes github issue #945.
1 file changed