strocon: don't overcommit when making node fill plan

[VladLazar]

Problem

The fill requirement was not taken into account when looking through the shards of a given node to fill from.

Summary of Changes

Ensure that we do not fill a node past the recommendation from Scheduler::compute_fill_requirement.

Checklist before requesting a review

• I have performed a self-review of my code.
• If it is a core feature, I have added thorough tests.
• Do we need to implement analytics? if so did you add the relevant metrics to the dashboard?
• If this PR requires public announcement, mark it with /release-notes label and add several sentences in this section.

Checklist before merging

• Do not forget to reformat commit message to not include the above checklist

[github-actions]

2910 tests run: 2793 passed, 0 failed, 117 skipped (full report)

---

Code coverage* (full report)

• functions: 32.8% (6888 of 21016 functions)
• lines: 50.3% (53882 of 107180 lines)

* collected from Rust tests only

---

_{The comment gets automatically updated with the latest test results
17bfdd2 at 2024-06-26T15:25:03.753Z :recycle:}