bz69439 - fix: improper handling of conflicting cache-control directives

[Chenjp]

Currently ExpiresFilter pickup the first-added cache-control header as the effective field, cause follow-up directives (like no-store or max-age) to be ignored.

rfc9111 - 4.2.1 - If directives conflict (e.g., both max-age and no-cache are present), the most restrictive directive should be honored.

• remove cacheControlHeader from servlet response wrapper ExpiresFilter.XHttpServletResponse.
• go through all cache-control fields when verify add-expire-header possibility.
• test case added.

[markt-asf]

Thanks for the PR. I have applied a fix based on this PR.

Removing the cache-control header caching removes a deliberate performance optimisation (and doesn't update the Javadoc to reflect that change either). I opted for the simpler approach of merging multiple headers into a single header in the cache. I also slightly changed the test cases.