Based on feedback from several members of the community, we have
decided to revert the caching of the Content-Type header that was
introduced in ContentCachingResponseWrapper in 375e0e6827.
This commit therefore completely removes Content-Type caching in
ContentCachingResponseWrapper and updates the existing tests
accordingly.
To provide guards against future regressions in this area, this commit
also introduces explicit tests for the 6 ways to set the content length
in ContentCachingResponseWrapper and modifies a test in
ShallowEtagHeaderFilterTests to ensure that a Content-Type header set
directly on ContentCachingResponseWrapper is propagated to the
underlying response even if content caching is disabled for the
ShallowEtagHeaderFilter.
See gh-32039
See gh-32317
Closes gh-32321
d1b3107398