docs: Remove troubleshooting for charlock_holmes 0.7.5 with icu4c 61.1

What does this Merge Request do and why?

Removes docs on troubleshooting for charlock_holmes 0.7.5 with icu4c 61.1, originally introduced in !450 (merged) in 2018 (GitLab %10.7).

Root cause was addressed by updating charlock_holmes gem from 0.7.5 to 0.7.6 on the upstream:

• gitlab-org/gitlab-foss in gitlab-foss!18103 (merged) (or gitlab@a951b96b)
• Gitaly in gitaly!649 (merged)

Merge Request checklist

• This change is backward compatible. If not, please include steps to communicate to our users.
• [n/a] Tests added for new functionality. If not, please raise Issue to follow-up.
• Documentation added/updated, if needed.
• [n/a] gdk doctor test added, if needed.
• [n/a] Add the ~highlight label if this MR should be included in the CHANGELOG.md.