Replace MemcachedCache backend with PymemcacheCache in insights

[iamsobanjaved]

The django.core.cache.backends.memcached.MemcachedCache backend is removed so we now are replacing this with PymemcacheCache in all of our IDAs, so we need to replace this for insights also.

This service is deployed with GoCD.

https://docs.djangoproject.com/en/4.2/releases/4.1/#features-removed-in-4-1

Things to be done:

• First, add pymemcache dependency in the codebase and move it to PROD
• Update the relevant configs for sandbox in sandbox-internal
• Update the relevant configs for stage in edx-internal
• Update the relevant configs for prod in edx-internal
• Update the relevant configs for edge in edge-internal
• Update the configs in related codebase so that the docker images of that service also get updated

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These are the config related changes which we will do:

• Update the backend
  • https://github.com/edx/sandbox-internal/blob/master/sandbox-remote-config/sandbox/lms.yml#L58
• Add extra parameters for pymemcache hashclient to enable pooling. It will make the client thread-safe.
  • https://github.com/edx/sandbox-internal/blob/master/sandbox-remote-config/sandbox/lms.yml#L63-L66

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One more thing to add:

• The IDA/services which are using edx-django-utils as their direct-dependency. We will enable edx_django_utils.cache.disable_forced_cache_miss_for_none waffle switch for them from their admin panel link to doc