1. It defaults to `cache: true` already
2. Setting it to `false` for non-GET request doesn't do anything
3. We were correcting `cache: false` GET requests to use `cache: true`
…so setting it to anything at all, for any type of request doesn't make sense (anymore)
* DEV: Move `Discourse.getURL` and related functions to a module
* DEV: Remove `Discourse.getURL` and `Discourse.getURLWithCDN`
* FIX: `get-url` is required for server side code
* DEV: Deprecate `BaseUri` too.
This reverts commit 20780a1eee.
* SECURITY: re-adds accidentally reverted commit:
03d26cd6: ensure embed_url contains valid http(s) uri
* when the merge commit e62a85cf was reverted, git chose the 2660c2e2 parent to land on
instead of the 03d26cd6 parent (which contains security fixes)
