fix(a11y): Unified search headings the sequel

[Pytal]

• For [BITV] 9.1.3.1a/9.1 - The page lacks an "h1" heading, and the existing "h2" heading, "Groups," does not accurately describe the content of the page and therefore cannot serve as the main heading for the page. (1) #41829

Summary

• Bring fix(a11y): Unified search headings #42111 in again after being lost in rebase-land with Rename "global search" to "unified search" #42094 🙈
• Fix heading styles

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[emoral435]

LGTM - also love the PR name LOL

[susnux]

LGTM! Just rebase :)

[susnux]

/backport cf0e32a to stable28

[backportbot-nextcloud]

The backport to stable28 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable28
git pull origin stable28

# Create the new backport branch
git checkout -b fix/foo-stable28

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts. Resolve them.
git cherry-pick abc123

# Push the cherry pick commit to the remote repository and open a pull request
git push origin fix/foo-stable28

Error: Unknown error

More info at https://docs.nextcloud.com/server/latest/developer_manual/getting_started/development_process.html#manual-backport

[susnux]

/backport cf0e32a to stable28

[backportbot-nextcloud]

The backport to stable28 failed. Please do this backport manually.

# Switch to the target branch and update it
git checkout stable28
git pull origin stable28

# Create the new backport branch
git checkout -b fix/foo-stable28

# Cherry pick the change from the commit sha1 of the change against the default branch
# This might cause conflicts. Resolve them.
git cherry-pick abc123

# Push the cherry pick commit to the remote repository and open a pull request
git push origin fix/foo-stable28

Error: Unknown error

More info at https://docs.nextcloud.com/server/latest/developer_manual/getting_started/development_process.html#manual-backport

[skjnldsv]

/skjnldsv-backport cf0e32a to stable28