ref(dev): Consolidate .gitignore files (#5096)

This removes `.gitignore` files containing redundant entries (ones covered by the main `.gitignore`) and organizes the main `.gitignore` just a bit. It also removes the old build directories, `cjs` and `esm`, from the main `.gitignore`.

Author: lobsterkatie

.gitignore

@@ -4,15 +4,16 @@ packages/*/package-lock.json
 package-lock.json
 
 # build and test
+# SDK builds
 build/
-packages/*/cjs/
-packages/*/esm/
+# various integration test builds
+dist/
 coverage/
 scratch/
+*.d.ts
+*.js.map
 *.pyc
 *.tsbuildinfo
-scenarios/*/dist/
-dist-serverless/
 # transpiled transformers
 jest/transformers/*.js
 # node tarballs
@@ -45,5 +46,3 @@ tmp.js
 # eslint
 .eslintcache
 eslintcache/*
-
-*.d.ts

packages/integration-tests/.gitignore

@@ -0,0 +1 @@
+dist-serverless/