Put `ExecutionContext` inside the Tx context

[mamcx]

Description of Changes

As a preparatory step for further PRs, like those related to the new Query Engine, most usages of ExecutionContext as an additional context in database calls are removed and put inside the Tx contexts instead.

API and ABI breaking changes

• This pr touches everything related to the db
• It could change the metrics. There were many places where the ExecutionContext was overwritten and now it should provide more exact measurements.
• Is necessary to check if it passes correctly the Identity & Address of replicas

Expected complexity level and risk

3

Testing

Describe any testing you've done, and any testing you'd like your reviewers to do, so that you're confident that all the changes work as expected!

• [x] Write a test you've completed here.
• [ ] Write a test you want a reviewer to do here, so they can check it off when they're satisfied.

[joshua-spacetime]

@cloutiertyler this is ready for your approval

[mamcx]

@cloutiertyler this is ready for your approval

Pls wait until I merge https://github.com/clockworklabs/SpacetimeDB/pull/1880 so it will be easier to read...

Ok, now is done!