Fix remaining MESH tests

Tests not passing in PTS v8.1.2 after Mesh sync https://github.com/apache/mynewt-nimble/pull/1062

- MESH/NODE/NET/BV-07-C
- MESH/NODE/NET/BV-14-C
- MESH/NODE/RLY/BV-02-C
- MESH/NODE/TNPT/BV-13-C
- MESH/NODE/IVU/BV-04-C
- MESH/NODE/FRND/FN/BV-12-C
- MESH/NODE/FRND/FN/BV-20-C
- MESH/NODE/FRND/LPN/BV-02-C
- MESH/SR/PROX/BV-14-C
- MESH/SR/MPXS/BV-09-C

Among these there are 4 tests that pass when BLE_MESH_SETTINGS is off:

- MESH/NODE/TNPT/BV-13-C
- MESH/NODE/FRND/LPN/BV-02-C
- MESH/NODE/FRND/FN/BV-12-C
- MESH/NODE/IVU/BV-04-C

Following test end up in watchdog timeout:

- MESH/NODE/NET/BV-07-C
- MESH/NODE/NET/BV-14-C
- MESH/NODE/RLY/BV-02-C

Start by reproducing the ten listed MESH tests against PTS v8.1.2, comparing runs with BLE_MESH_SETTINGS enabled and disabled. Focus first on the three cases reported to hit the watchdog timeout, then verify the other failures. Done means all listed tests pass with BLE_MESH_SETTINGS enabled and without watchdog timeouts.

Written by the indexing model from the issue text.