get rid of usages of substr which is deprecated

Signed-off-by: Fredrik Adelöw <freben@gmail.com>

.changeset/shy-steaks-invite.md

@@ -0,0 +1,16 @@
+---
+'@backstage/plugin-catalog-backend-module-bitbucket': patch
+'@backstage/plugin-catalog-backend-module-github': patch
+'@backstage/plugin-catalog-backend-module-gitlab': patch
+'@backstage/plugin-catalog-backend-module-azure': patch
+'@backstage/plugin-azure-devops-backend': patch
+'@backstage/plugin-git-release-manager': patch
+'@backstage/core-components': patch
+'@backstage/plugin-playlist-backend': patch
+'@backstage/plugin-apache-airflow': patch
+'@backstage/plugin-circleci': patch
+'@backstage/plugin-bitrise': patch
+'@backstage/plugin-sentry': patch
+---
+
+Internal refactor to not use deprecated `substr`