Merge "Fixing tracfone AT&T mmsproxy to remove http:// from value" am: 79eabcac09 am: 63f3080c13 am: dcb15963d8

Original change: https://android-review.googlesource.com/c/device/sample/+/2039583

Change-Id: Ibcc4d0809c0ad7bdde6efe48646b52214bb409d5