Fix Perl client header params

[7474]

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The following error occurred when using the DELETE method.

Not a HASH reference at /app/local/lib/perl5/HTTP/Headers.pm line 160.

Matched the header settings of the DELETE method with GET and HEAD.
I also deleted unreferenced variables.

@wing328 @yue9944882

[wing328]

@7474 thanks for the PR. Can you please fix the merge conflicts when you've time? PM via Slack if you need help.

[wing328]

Tested locally and the result is good. Thanks for the PR.