chore: fix the init task for gitpod (#21064)

This PR fixes the init task in `.gitpod.yml` for gitpod to correctly prebuild and remove the eslint static version pinning.

Fixes: #21063 

----

### All Submissions:

* [v] Have you followed the guidelines in our [Contributing guide?](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md)

### Adding new Unconventional Dependencies:

* [ ] This PR adds new unconventional dependencies following the process described [here](https://github.com/aws/aws-cdk/blob/main/CONTRIBUTING.md/#adding-new-unconventional-dependencies)

### New Features

* [ ] Have you added the new feature to an [integration test](https://github.com/aws/aws-cdk/blob/main/INTEGRATION_TESTS.md)?
	* [ ] Did you use `yarn integ` to deploy the infrastructure and generate the snapshot (i.e. `yarn integ` without `--dry-run`)?

*By submitting this pull request, I confirm that my contribution is made under the terms of the Apache-2.0 license*

.gitpod.yml

@@ -6,8 +6,8 @@ github:
 image: jsii/superchain:1-buster-slim
 
 tasks:
-  - init: yarn build --skip-test --no-bail --skip-prereqs --skip-compat
+  - init: yarn install && ./scripts/foreach.sh yarn build
 
 vscode:
   extensions:
-    - dbaeumer.vscode-eslint@2.1.20
+    - dbaeumer.vscode-eslint