fix(files_sharing): rate limit share creation 40 times per 10 minutes

[biredel]

Share creation was unlimited before #50905 setting to 20/600s. That proved to be too low for (integration tests, and more crucially) some legitimate human actions, e.g. chat messages with attachments in Talk.

• Resolves: [Bug]: Default share creation rate limit breaks typical human usage, e.g. in 429 in Talk app #57665 by bumping to some arbitrary higher value, until some clearer justification for having it lower or higher is determined.

Checklist

• What is partially reverted here was already manually exempt from testing
• No font-end changes
• Documentation update not required
• Backports requested where applicable (ex: critical bugfixes)
• Labels added where applicable (ex: bug/enhancement, 3. to review, feature component)
• Milestone added for target branch/version (ex: 32.x for stable32)

[github-actions]

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