Revert CI no-output timeout

[julianrex]

Follow on from #60:

We had to bump the CI no-output timeout to 20m (up from 5m) - this should be considered a short-term measure.

Let's investigate a solution here - which may involve disabling parallel builds for the relevant schemes.

[julianrex]

/cc @nishant-karajgikar

[misterkerry]

@julianrex: trying various versions with 0m timeouts and increments up to 20m ....looking into toggling parallel builds as well.

[misterkerry]

@julianrex trying this config all week...see if it passes.

[stale]

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