Azure CI: Restrict integration builds to merges and releases
Azure CI: Restrict integration builds to merges and releases

Reduce CI build count by restricting 'CI build' (azure terminology) to the dev and release branches. PRs should still
build separately, and our branch protection settings restrict merges to passing CI with branch rebased against latest dev.

This cuts down the build count to 1 per PR push, plus 1 at merge, instead of 2 per PR push.

TileDB-Inc/TileDB,TileDB-Inc/TileDB,TileDB-Inc/TileDB,TileDB-Inc/TileDB