[improvement] set log level for node_controller to higher level than default to reduce spam

[AshleyDumaine]

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Changes

Node controller prints a log message every time a node updates. On large clusters, this creates a spam that makes reading logs difficult and consumes storage space unnecessarily.
By default, the CCM logs at level 3. Since these are more of a debugging message, I've explicitly set the level of them to 4.

[codecov]

Codecov Report

❌ Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 73.65%. Comparing base (916513b) to head (d954499).

Files with missing lines	Patch %	Lines
cloud/linode/node_controller.go	50.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #587   +/-   ##
=======================================
  Coverage   73.65%   73.65%           
=======================================
  Files          19       19           
  Lines        3029     3029           
=======================================
  Hits         2231     2231           
  Misses        538      538           
  Partials      260      260           

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