Various fix-ups on HTTP tests.
* jk/http-test-fixes:
t5559: make SSL/TLS the default
t5559: fix test failures with LIB_HTTPD_SSL
t/lib-httpd: enable HTTP/2 "h2" protocol, not just h2c
t/lib-httpd: respect $HTTPD_PROTO in expect_askpass()
t5551: drop curl trace lines without headers
t5551: handle v2 protocol in cookie test
t5551: simplify expected cookie file
t5551: handle v2 protocol in upload-pack service test
t5551: handle v2 protocol when checking curl trace
t5551: stop forcing clone to run with v0 protocol
t5551: handle HTTP/2 when checking curl trace
t5551: lower-case headers in expected curl trace
t5551: drop redundant grep for Accept-Language
t5541: simplify and move "no empty path components" test
t5541: stop marking "used receive-pack service" test as v0 only
t5541: run "used receive-pack service" test earlier
b2893ea403