ini: drop setting initial_repo_scan The ini setting 'initial_repo_scan' caused a repository scan on each startup of Kallithea. The accompanying comment already warns that the feature should be disabled after the first run to improve startup time. Now that setup-db is performing the initial repository scan, and considering that administrators can always request a new scan using 'gearbox repo-scan' or via the web interface, the 'initial_repo_scan' feature is no longer considered useful and is removed with this commit.