Refactor/Make CircleCI use blobs download scripts blobs placed under blobs dir + have CircleCI prep step download only if hashes of blobs fail

[tlaurion]

Working on #1570 the following next steps are needed

• dgpu blobs (t530 dgpu/w530 dgpu+igpu board flavors) scripts are complicated and fail to work under debian-12
• haswell blobs are downloaded at each builds per CI since not part of CircleCI prep step (650mb download to extract MRC blob!!!!)
• review scripts so that first step is to check extracted blobs existence + hash prior of redownloading (done for xx20_me/xx30_me but none other scripts)

[gaspar-ilom]

MRC blob downloads should not be an issue anymore after switching to NRI: #2025 but ME could be cached and re-used between T440p and W541. Currently, not the case I believe.