Revert "Merge branch 'a_mcdonald-master-patch-46738' into 'master'"

What does this MR do and why?

Fixes #372186 (closed)

The test was updated after !95859 (merged) updated the Content-Type.
However a follow up MR !96398 (merged) adds an exception for SVGs so we should expect to get a Content-Type: image/svg+xml response in this spec.

This MR reverts the test back to the original state.

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