Change health check period based on timeout

[weiiwang01]

Overview

Change the health check period to be twice the health check timeout value. This is required because Pebble versions below 1.7 need the health check timeout value to be less than the health check period value. And newer Pebble versions will clamp the timeout value to be less than or equal to the health check period.

Checklist

• The charm style guide was applied
• The contributing guide was applied
• The changes are compliant with ISD054 - Managing Charm Complexity
• The documentation is generated using src-docs
• The documentation for charmhub is updated.
• The PR is tagged with appropriate label (urgent, trivial, complex)

[hloeung]

LGTM, thanks!

[github-actions]

Test coverage for b902dcd

Name                Stmts   Miss Branch BrPart  Cover   Missing
---------------------------------------------------------------
src/charm.py          557     35    190     34    91%   162, 204-207, 299->302, 414, 473->477, 626, 657, 663, 680-684, 714, 749-750, 810, 819, 923->936, 935, 937, 942-943, 1003, 1023, 1030, 1120, 1129, 1141, 1162, 1171, 1190, 1194, 1223, 1264, 1396, 1418, 1425->1427, 1470->exit, 1482, 1492, 1530
src/cos.py             20      0      0      0   100%
src/exceptions.py      16      1      2      1    89%   41
src/state.py           33      0      4      0   100%
src/types_.py          15      0      0      0   100%
---------------------------------------------------------------
TOTAL                 641     36    196     35    92%

Static code analysis report

Run started:2024-09-18 17:18:04.662339

Test results:
  No issues identified.

Code scanned:
  Total lines of code: 4644
  Total lines skipped (#nosec): 1
  Total potential issues skipped due to specifically being disabled (e.g., #nosec BXXX): 0

Run metrics:
  Total issues (by severity):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
  Total issues (by confidence):
  	Undefined: 0
  	Low: 0
  	Medium: 0
  	High: 0
Files skipped (0):