Adjust max squid cache time also for tftp metadata

[aaannz]

What does this PR change?

#9602 modified maximum squid cache time to proper 5 minutes, but did not modify tftp metadata timeout. This PR adjust that to 5 minutes as well.

I chose not to write new changelog entry as this can be covered by changelog provided by @mcalmer in mentioned PR.

GUI diff

No difference.

• DONE

Documentation

• No documentation needed: only internal and user invisible changes

• DONE

Test coverage

ℹ️ If a major new functionality is added, it is strongly recommended that tests for the new functionality are added to the Cucumber test suite

• No tests: add explanation

• DONE

Links

Issue(s): #
Port(s): # add downstream PR(s), if any

• DONE

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