fix(ci): lint translations with locale-specific Vale rules

What does this MR do and why?

Adding French translations failed the docs lint job with 154 errors, none of them real. The job checked translated pages against the English style guide, which bans the no-break space and the space before a colon that French typography requires. Each locale now has its own Vale configuration, so translations are checked with locale-appropriate rules only. English documentation linting is unchanged. This matches how the main GitLab repository handles its translations.

Related Issues

Prompted by this failing job and currently blocking the four pending locale branches (GITTECHA-905 and GITTECHA-906, French and Korean).

Testing

Ran Vale locally against the real French content from docs-i18n/-GITTECHA-905-fr-FR-1:

• Before: 154 errors, all NonStandardSpaces or SentenceSpacing.
• After: 0 errors across French (20 files) and Japanese (36 files).
• English docs/source still lints clean (31 files, 0 errors), so the root config change does not weaken English checks.
• Confirmed the job fails with an actionable message if a locale ships translations without a configuration file.

Performance Analysis

CI-only change, no runtime code touched. The lint job now invokes Vale once per locale rather than once overall, which is negligible at this scale.

• This merge request does not introduce any performance regression. If a performance regression is expected, explain why.

Agent context — long-form analysis, file-by-file walkthroughs, profiler output, alternatives considered

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