check-docker-context file count is unstable

[alxndrsn]

The differences appear to come from changes in the .git dir.

Examples - repeated job on same CI run:

• https://github.com/alxndrsn/odk-central/actions/runs/24387253287/job/71234193262 - 1732 files
• https://github.com/alxndrsn/odk-central/actions/runs/24387253287/job/71224176658 - 1729 files

Differences:

638,643c638,640
< ./.git/objects/pack/pack-9965b4e17949f2cabc5d30242619a69bc52001c6.idx
< ./.git/objects/pack/pack-9965b4e17949f2cabc5d30242619a69bc52001c6.rev
< ./.git/objects/pack/pack-b6f01a515c37419d293c2192984f5ab33646d880.idx
< ./.git/objects/pack/pack-b6f01a515c37419d293c2192984f5ab33646d880.rev
< ./.git/objects/pack/pack-b6f01a515c37419d293c2192984f5ab33646d880.pack
< ./.git/objects/pack/pack-9965b4e17949f2cabc5d30242619a69bc52001c6.pack
---
> ./.git/objects/pack/pack-3d098af647a8b0a7b34bc9e1175918670d9eeb76.pack
> ./.git/objects/pack/pack-3d098af647a8b0a7b34bc9e1175918670d9eeb76.rev
> ./.git/objects/pack/pack-3d098af647a8b0a7b34bc9e1175918670d9eeb76.idx
791,793c788,790
< ./.git/modules/server/objects/pack/pack-669d6cf2000e949aa7d9b7bc83639f87d899ee90.pack
< ./.git/modules/server/objects/pack/pack-669d6cf2000e949aa7d9b7bc83639f87d899ee90.rev
< ./.git/modules/server/objects/pack/pack-669d6cf2000e949aa7d9b7bc83639f87d899ee90.idx
---
> ./.git/modules/server/objects/pack/pack-dc07faa2e1965d910e769ffd5fbd61ea59079ee1.pack
> ./.git/modules/server/objects/pack/pack-dc07faa2e1965d910e769ffd5fbd61ea59079ee1.rev
> ./.git/modules/server/objects/pack/pack-dc07faa2e1965d910e769ffd5fbd61ea59079ee1.idx