Revert restart intensity of external stats process

[luos]

Previously the restart intensity was 100 and period 50. This process was
prone to crashing in the past, so it does not make sense to not restart it
if anything happens during the gathering of statistics.

Related: #2850

The change was made at
70ca708#diff-f43c0b585b96bc55884ef0b857ded88454ff041395471f4710cea6c713dcdbc8L27
and probably it was unintended.

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[michaelklishin]

Yes, this wasn't intentional or related to Erlang 24.

[michaelklishin]

Backported to v3.8.x.

[luos]

Thank you! :)