made getSubscriptions into an iterator to reduce memory usage

[Gkrumbach07]

closes: https://issues.redhat.com/browse/RHOAIENG-2040

Description

The backend uses an old method of watching certain get requests and subscriptions were a part of that logic. The watcher code will pull the data on creation of the watcher so no matter what we were fetching up to 250 items. This can causes memory issues as these subscriptions can get big.

In this solution, we remove subscriptions form the watcher and instead implement a iterator. Now we pull 100 items at a time, don't store them in memory when fetch the next batch. And always exiting early on finding what we need

How Has This Been Tested?

Make a log statement in fetch subs function and check that it is pulling everything. Reach out to @Gkrumbach07 as he set up a cluster with 300+ operators subscriptions to test this better.

Test Impact

backend code n/a

Request review criteria:

Self checklist (all need to be checked):

• The developer has manually tested the changes and verified that the changes work
• Commits have been squashed into descriptive, self-contained units of work (e.g. 'WIP' and 'Implements feedback' style messages have been removed)
• Testing instructions have been added in the PR body (for PRs involving changes that are not immediately obvious).
• The developer has added tests or explained why testing cannot be added (unit tests & storybook for related changes)

If you have UI changes:

• Included any necessary screenshots or gifs if it was a UI change.
• Included tags to the UX team if it was a UI/UX change (find relevant UX in the SMEs section).

After the PR is posted & before it merges:

• The developer has tested their solution on a cluster by using the image produced by the PR to main

[Gkrumbach07]

/hold

[Gkrumbach07]

tested on a cluster and prevents error from occurring. I am not sure if we need to make the number of requests lower. Right now it queries 100 at a time

[andrewballantyne]

We tested this on Gage's cluster that had the reproduced env of 300+ subs -- this pod did not crash (we did see it crash on main).

[openshift-ci]

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