Settings: Hide section subheadings when searching for features

[scottsweb]

Since the module search might throw results that are not strictly encompassed in the current tab, the titles should be adjusted to provide context lost by the removed navigation.

Fixes #12091

Changes proposed in this Pull Request:

• Swap the subheadings to match the section navigation during a module search

Testing instructions:

• Go to Jetpack settings
• Click on the magnifying glass to start searching
• type something that actually has results, like "search"
• check the subheadings correctly separate the sections and make sense

Before:

After:

Proposed changelog entry for your changes:

• Clearer headings when searching for modules in the settings section

[jetpackbot]

Thank you for the great PR description!

When this PR is ready for review, please apply the [Status] Needs Review label. If you are an a11n, please have someone from your team review the code if possible. The Jetpack team will also review this PR and merge it to be included in the next Jetpack release.

Scheduled Jetpack release: May 7, 2019.
Scheduled code freeze: April 30, 2019

Generated by 🚫 dangerJS against def17e7

[MichaelArestad]

Tested. This is excellent. Once crew reviews, I would say this is ready to merge.

[jeherve]

This works well in my tests. Merging!