[test] improves wiring/no_fixture_long_running NETWORK_XX test timing

[technobly]

Problem

wiring/no_fixture_long_running NETWORK_02 and possibly 01 or 03 can fail when a device takes longer than expected to register. We test connect_time cold/warm boots separately with a 75th percentile criteria after 8 runs. Here, we only run through once and it would be kind of lengthy to run this test 8 or even 4 times.

Solution

Instead of running multiple times and taking a percentile of runs, like 3 out of 4, if we increase the wait time from 10 minutes to 15 minutes, we give Device OS a chance to go through it's 10 minute "Resetting the modem due to the network registration timeout", and a bit extra in case of other network related timers causing an issue.

Steps to Test

• run wiring/no_fixture_long_running NETWORK_02 in a loop on multiple devices at once while logging the output.

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Completeness

• User is totes amazing for contributing!
• Contributor has signed CLA (Info here)
• Problem and Solution clearly stated
• Run unit/integration/application tests on device
• Added documentation
• Added to CHANGELOG.md after merging (add links to docs and issues)