chore: fix various e2e test setup issues (#12670)

I noticed a few issues when running e2e tests that will be resolved by
this PR:

- Most important: for some test suites (fields, fields-relationship,
versions, queues, lexical), the database was cleared and seeded
**twice** in between each test run. This is because the onInit function
was running the clear and seed script, when it should only have been
running the seed script. Clearing the database / the snapshot workflow
is being done by the reInit endpoint, which then calls onInit to seed
the actual data.
- The slowest part of `clearAndSeedEverything` is recreating indexes on
mongodb. This PR slightly improves performance here by:
- Skipping this process for the built-in `['payload-migrations',
'payload-preferences', 'payload-locked-documents']` collections
- Previously we were calling both `createIndexes` and `ensureIndexes`.
This was unnecessary - `ensureIndexes` is a deprecated alias of
`createIndexes`. This PR changes it to only call `createIndexes`
- Makes the reinit endpoint accept GET requests instead of POST requests
- this makes it easier to debug right in the browser
- Some typescript fixes
- Adds a `dev:memorydb` script to the package.json. For some reason,
`dev` is super unreliable on mongodb locally when running e2e tests - it
frequently fails during index creation. Using the memorydb fixes this
issue, with the bonus of more closely resembling the CI environment
- Previously, you were unable to run test suites using turbopack +
postgres. This fixes it, by explicitly installing `pg` as devDependency
in our monorepo
- Fixes jest open handles warning

test/generateDatabaseAdapter.ts

@@ -11,6 +11,8 @@ export const allDatabaseAdapters = {
 
   export const databaseAdapter = mongooseAdapter({
     ensureIndexes: true,
+    // required for connect to detect that we are using a memory server
+    mongoMemoryServer:  global._mongoMemoryServer,
     url:
       process.env.MONGODB_MEMORY_SERVER_URI ||
       process.env.DATABASE_URI ||