[automerger] Reduce max keymaster message size to 2K am: a0b9b39647  -s ours am: 065e4397cd am: 9838c48dfe am: 9e2a045edf
am: f7acad81c1

Change-Id: Ida0e394f1a904ceb7f168c0860a4291c0b53f9a7