Reevaluate symbol request lifetime

- [ ] This issue is blocking
- [x] This issue is causing unreasonable pain

Right now, symbol requests are allowed to live for too long. In just a few months we've generated 20TB of symbol data that's to live for 10 years. Most of these symbols are not necessary. We should change it to the following:

- Channels/repos that are contributing to the current UB main, symbols are retained for 90 days
- Release branch channels of regular channels retain 6 months per build.
- Release branch channels of tools channels retain 10 years.
- Staging and release pipeline retain for 10 years as we currently do.

@jaredpar @marcpopMSFT do these line up well for insertion scenarios?

cc @mmitche