Degradation example update

[DrSOKane]

The experiment protocol for the coupled degradation example notebook was changed so that the 5 minute period applied to all stepts of all cycles, including the 1C discharge. This results in the simulation being unstable for large numbers of cycles. This pull request reverts the change and fixes the issue.

Fixes #3669

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

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[kratman]

The change looks good. You have some really old commits on this branch though. The other PR you closed was from your develop branch and did the same thing. My guess is that you should reset your develop branch to the main pybamm develop branch

[kratman]

The change looks good. You have some really old commits on this branch though. The other PR you closed was from your develop branch and did the same thing. My guess is that you should reset your develop branch to the main pybamm develop branch

Also you have some reverts, so it might be best to squash this PR to a single commit

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (d46cbe3) 99.59% compared to head (a5f2d68) 99.59%.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #3691   +/-   ##
========================================
  Coverage    99.59%   99.59%           
========================================
  Files          258      258           
  Lines        20796    20796           
========================================
  Hits         20711    20711           
  Misses          85       85           

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