Override PECL related env vars required for using PHP runtime
Override PECL related env vars required for using PHP runtime

PiperOrigin-RevId: 444594587
Change-Id: I6146e79d98a3be88ca3f91385f9339416ad99396

GoogleCloudPlatform/buildpacks,GoogleCloudPlatform/buildpacks,GoogleCloudPlatform/buildpacks,GoogleCloudPlatform/buildpacks