Mostly Revert "Revert "Moving the buildDir for the buildSrc project to be in the out/ dir""

This mostly reverts commit 5bf892ecb54bfa053994e7318bdfbd5210330629 but also fixes the creation of a dir named "null" by Studio

Test: rm ../../out null -rf && ./studiow && sleep 30 && ls ../../out && ls null # and make sure 'null' does not exist
Test: OUT_DIR=/tmp/out DIST_DIR=/tmp/out/dist ./gradlew buildOnServer && ls /tmp/out/dist/top-of-tree-m2repository-partially-dejetified-dist.zip
Test: ./cleanBuild.sh assembleDebug && ls ../../out/dist
Test: git clean -fdx && ./gradlew projects && ((stat buildSrc/build && echo failed: buildSrc/build must not exist) || true)
Test: OUT_DIR=/tmp/out DIST_DIR=/tmp/out/dist ./gradlew misspelledTaskName # and see that there's a stacktrace
Test: ./gradlew misspelledTaskName # and see that there's no stacktrace

Change-Id: I0577fa2d4d961d5357badc17d936102918f9dc76

diff --git a/cleanBuild.sh b/cleanBuild.sh
index 5ac9302..90d0861 100755
--- a/cleanBuild.sh
+++ b/cleanBuild.sh

@@ -27,9 +27,8 @@
 
 export OUT_DIR=../../out
 function removeCaches() {
-  rm -rf .gradle 
+  rm -rf .gradle
   rm -rf buildSrc/.gradle
-  rm -rf buildSrc/build
   rm -f local.properties
   rm -rf ../../out
 }