Fix glitch of password manager button in dark themes (macOS Safari)

[Iksas]

• What does this PR aim to accomplish?:

This PR fixes a glitch with the password manager button in dark themes that affects macOS Safari.

Before:

After:

• How does this PR accomplish the above?:

In #2020, a workaround was introduced to fix the appearance of the password manager button on dark backgrounds in macOS Safari. Apple has since fixed the issue. The workaround now breaks the button, so it has been removed.

(The workaround for the caps lock button also introduced in #2020 is still needed, and works fine.)

• What documentation changes (if any) are needed to support this PR?:

none

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[yubiuser]

Thanks for your PR. Could you please rebase on latest devel and force push?

[Iksas]

Ah my bad. Now it should be fixed.

[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/pi-hole-ftl-v5-18-1-web-v5-15-1-and-core-v5-12-2-released/58022/1