refactor: simplify c8y_http_proxy #6714

Job	Run time
Block fixup commits	16s
Check whether Cargo.lock is up to date	1m 29s
Filter changes	4s
Shellcheck	10s
Spell Check with Typos	6s
Run cargo clippy	2m 1s
Run cargo test	17s
Run cargo audit	11s
Run cargo check on MSRV	1m 37s
Sort dependencies	2m 7s
Run format checks	5m 41s
nightly / doc	1m 33s
Check for unused dependencies	6m 52s
Check markdown	0s
	22m 24s

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