src: Replace style overrides by component props where possible

[regexowl]

There are several style overrides sprinkled through the code base, we could get rid of at least some of them.

Examples:

• some buttons have a custom padding specified (pf-v5-u-p...), we could replace some of that with isInline prop https://v5-archive.patternfly.org/components/button#variant-examples
• some popover buttons have size specified via className, this might be nicer to specify via size="....." prop

This will not be possible in all cases, but if we can remove at least some overrides that would be nice, less work when migrating to PF6 in foreseeable future.