[com_plugins] Complete search tooltip

[andrepereiradasilva]

Summary of Changes

Very simple PR to improve the search tooltip and element label (accessibility) in com_plugins.

Testing Instructions

Code review, or:

1. Apply patch
2. Go to Extensions -> Plugins, check the tooltip in the search field.

[brianteeman]

I have tested this item ✅ successfully on 8f5f849

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[grhcj]

I have tested this item ✅ successfully on 8f5f849

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_{This comment was created with the J!Tracker Application at issues.joomla.org/joomla-cms/10172.}

[brianteeman]

Rtc

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_{This comment was created with the J!Tracker Application at issues.joomla.org/joomla-cms/10172.}