[a-g]: replace plist with service block

[SMillerDev]

• Have you followed the guidelines for contributing?
• Have you ensured that your commits follow the commit style guide?
• Have you checked that there aren't other open pull requests for the same formula update/change?
• Have you built your formula locally with brew install --build-from-source <formula>, where <formula> is the name of the formula you're submitting?
• Is your test running fine brew test <formula>, where <formula> is the name of the formula you're submitting?
• Does your build pass brew audit --strict <formula> (after doing brew install --build-from-source <formula>)? If this is a new formula, does it pass brew audit --new <formula>?

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[SMillerDev]

==> dig @127.0.0.1 -p 61416 example.com.
dyld: Library not loaded: /opt/homebrew/opt/json-c/lib/libjson-c.5.dylib
  Referenced from: /opt/homebrew/bin/dig
  Reason: image not found

and a checksum mismatch for ejabberd, not bad

[SMillerDev]

I don't think any of the errors are related to the service blocks. @Homebrew/core opinions?

[cho-m]

• carrot2 (Big Sur/Catalina) - Did pass when built+tested locally. May need to see if CI environment behaves differently or some other issue.
• coredns (All) - Previously mentioned. Seems like something odd about running Homebrew's dig (from bind formula?)

  dyld: Library not loaded: /usr/local/opt/json-c/lib/libjson-c.5.dylib
    Referenced from: /usr/local/bin/dig
  

• ejabberd (All) - Error: SHA256 mismatch
• fail2ban (Intel) - Unrelated missing build dependency in sphinx-doc (sphinx-doc: restore numpydoc resource for fail2ban build #79892).
• lanraragi (ARM) - Looks like common test failure seen in other PRs.
• cntlm (Mojave) - Temporary network issue

[SMillerDev]

I dropped the formulae that were having issues. We can always revisit those later (when cron support is added and we can drop the Plists completely)

[carlocab]

lanraragi failed on ARM, but that test is flaky (despite my attempts to fix it...). We can probably ignore it.

[SMillerDev]

Fails only on ubuntu due to missing dependencies. @carlocab good to merge?

[carlocab]

Do we need new bottles for this? If yes, unfortunately not: the ARM runner died 19m into the CI run for some reason. If we don't, then I'm fine with merging this.

[SMillerDev]

Nope, it's all in postinstall.