Fix dashboard dimension search bug

[ericokuma]

Fixes APP-581: Dashboard dimension search failing with trailing spaces.

Previously, searching for a dimension with a trailing space (e.g., "site ") would incorrectly return "No matching dimensions". This change trims the search input before filtering, ensuring that leading or trailing whitespace does not interfere with matching dimensions.

Checklist:

• Covered by tests
• Ran it and it works as intended
• Reviewed the diff before requesting a review
• Checked for unhandled edge cases
• Linked the issues it closes
• Checked if the docs need to be updated. If so, create a separate Linear DOCS issue
• Intend to cherry-pick into the release branch
• I'm proud of this work!

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Linear Issue: APP-581