Fix instructions for running acceptance tests (#10846)

1) Remove requirement for local Postgres, because it is no longer needed
2) Fix bash code snippet for running acceptance tests (remove the line that starts Airbyte)
3) Document how to use USE_EXTERNAL_DEPLOYMENT flag

docs/contributing-to-airbyte/developing-locally.md

@@ -6,8 +6,7 @@ The following technologies are required to build Airbyte locally.
 2. `Node 16`
 3. `Python 3.7`
 4. `Docker`
-5. `Postgresql`
-6. `Jq`
+5. `Jq`
 
 {% hint style="info" %}
 Manually switching between different language versions can get hairy. We recommend using a version manager such as [`pyenv`](https://github.com/pyenv/pyenv) or [`jenv`](https://github.com/jenv/jenv).
@@ -83,14 +82,19 @@ In `dev` mode, all data will be persisted in `/tmp/dev_root`.
 
 ## Run acceptance tests
 
-To run acceptance \(end-to-end\) tests, you must have the Airbyte running locally.
+To run acceptance \(end-to-end\) tests:
 
 ```bash
 SUB_BUILD=PLATFORM ./gradlew clean build
-VERSION=dev docker-compose up
 SUB_BUILD=PLATFORM ./gradlew :airbyte-tests:acceptanceTests
 ```
 
+Test containers start Airbyte locally, run the tests, and shutdown Airbyte after running the tests. If you want to run acceptance tests against local Airbyte that is not managed by the test containers, you need to set `USE_EXTERNAL_DEPLOYMENT` environment variable to true:
+
+```bash
+USE_EXTERNAL_DEPLOYMENT=true SUB_BUILD=PLATFORM ./gradlew :airbyte-tests:acceptanceTests 
+```
+
 ## Run formatting automation/tests
 
 Airbyte runs a code formatter as part of the build to enforce code styles. You should run the formatter yourself before submitting a PR (otherwise the build will fail).