Issue Summary
The new External System Import experience (CSV importer) does not support searching for a space by space key, only space name is recognized.

This creates friction for users who know their space key but not the exact space name, which is common in large Jira instances with many spaces.

Steps to Reproduce

1. Navigate to Settings → System → External System Import and select CSV

2. On the space selection screen, choose "Use settings from an existing space" and type a space key (e.g. KEYB) into the search field

Expected Results
The space search field should return matching results when searching by either space name or space key, consistent with how space search works elsewhere in Jira (e.g., work item navigator, board search).

Actual Results
Searching by space key returns no results. Only searches by space name return matching spaces. Users must know the exact space name to proceed, which is unintuitive and inconsistent with the rest of the Jira UI.

Workaround
Search for the space using its full or partial space name instead of the space key.