fix: respect caller-provided server capabilities

[1yuxiangJ]

Fixes #1086

Problem

McpAsyncServer unconditionally advertises the logging capability,
even when the caller did not configure it.

Changes

• Preserve the caller-provided server capabilities
• Stop implicitly advertising logging
• Cover both server transport construction paths
• Add regression tests
• Explicitly configure logging in the existing logging integration test

Testing

Passed:

./mvnw -pl mcp-core -Dtest=McpAsyncServerCapabilitiesTests test
./mvnw -pl mcp-core test
./mvnw -pl mcp-test -am \
  -Dtest=HttpServletSseIntegrationTests#testLoggingNotification,HttpServletStreamableIntegrationTests#testLoggingNotification \
  -Dsurefire.failIfNoSpecifiedTests=false test