PR #109318 - base: add env vars for RPC settings

[cockroach-teamcity]

Exalate commented:

Related PR: cockroachdb/cockroach#109318
Commit: cockroachdb/cockroach@1f6b3d0
Epic: none

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Release note (ops change): The RPC dial and heartbeat timeouts can now
be configured via the environment variables COCKROACH_RPC_DIAL_TIMEOUT
(default 2x COCKROACH_NETWORK_TIMEOUT or 2x2=4 seconds) and
COCKROACH_RPC_HEARTBEAT_TIMEOUT (default 3x COCKROACH_NETWORK_TIMEOUT or
3x2=6 seconds). This allows configuring these values independently of
COCKROACH_NETWORK_TIMEOUT.

Jira Issue: DOC-8649