add X-Content-Type-Options header

[xavpaice]

What this PR does / why we need it:

Adds X-Content-Type-Options header.

Which issue(s) this PR fixes:

[SC-134654]

Does this PR require a test?

NONE

Does this PR require a release note?

Admin Console now includes X-Content-Type-Options header

Does this PR require documentation?

NONE

[greptile-apps]

_{Reviews (1): Last reviewed commit: "add X-Content-Type-Options header" | Re-trigger Greptile}

[greptile-apps]

_{Reviews (2): Last reviewed commit: "Update pkg/handlers/middleware.go" | Re-trigger Greptile}

[greptile-apps]

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[greptile-apps]

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[greptile-apps]

_{Reviews (5): Last reviewed commit: "undo workflow changes that do not help" | Re-trigger Greptile}

[greptile-apps]

_{Reviews (6): Last reviewed commit: "increase timeout for validate-remove-app..." | Re-trigger Greptile}

[greptile-apps]

_{Reviews (7): Last reviewed commit: "roll back changes to workflow" | Re-trigger Greptile}