php: fix jenkins flake

src/php/bin/run_tests.sh

@@ -31,7 +31,11 @@
 # Loads the local shared library, and runs all of the test cases in tests/
 # against it
 set -e
-cd $(dirname $0)
+cd $(dirname $0)/../../..
+root=$(pwd)
+cd src/php/bin
 source ./determine_extension_dir.sh
+# in some jenkins macos machine, somehow the PHP build script can't find libgrpc.dylib
+export DYLD_LIBRARY_PATH=$root/libs/$config
 php $extension_dir $(which phpunit) -v --debug --strict \
   ../tests/unit_tests

tools/run_tests/build_php.sh

@@ -46,6 +46,3 @@ cd ext/grpc
 phpize
 ./configure --enable-grpc=$root
 make
-
-# in some jenkins macos machine, somehow the PHP build script can't find libgrpc.dylib
-export DYLD_LIBRARY_PATH=$(pwd)/libs/$config