php: ran php-cs-fixer to comply with php coding standard

src/php/bin/run_php_cs_fixer.sh

src/php/lib/Grpc/AbstractCall.php

src/php/lib/Grpc/BaseStub.php

src/php/lib/Grpc/BidiStreamingCall.php

src/php/lib/Grpc/ClientStreamingCall.php

src/php/lib/Grpc/ServerStreamingCall.php

src/php/lib/Grpc/UnaryCall.php

src/php/tests/generated_code/AbstractGeneratedCodeTest.php

src/php/tests/generated_code/GeneratedCodeTest.php

...hp/tests/generated_code/GeneratedCodeWithCallbackTest.php

src/php/tests/generated_code/math_client.php

src/php/tests/interop/interop_client.php

src/php/tests/unit_tests/CallTest.php

src/php/tests/unit_tests/EndToEndTest.php

src/php/tests/unit_tests/SecureEndToEndTest.php

src/php/tests/unit_tests/TimevalTest.php