Always use blob id as the name of the filecache when use separate blob

[zyfjeff]

Details

Before we only has one blob, called a data blob, so when generating a filecache, we always used the id of this blob as the name of the filecache, and later after supporting separate blobs, we has two blobs, one is a data blob, the other is a meta blob, in order to maintain compatibility, we should always use the data blob id as the filecache name, not the meta blob id.

Types of changes

What types of changes does your PullRequest introduce? Put an x in all the boxes that apply:

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation Update (if none of the other choices apply)

[codecov]

Codecov Report

Merging #1432 (2f987a2) into master (278915b) will decrease coverage by 0.27%.
Report is 4 commits behind head on master.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master    #1432      +/-   ##
==========================================
- Coverage   46.45%   46.19%   -0.27%     
==========================================
  Files         123      123              
  Lines       38640    38702      +62     
  Branches    38640    38702      +62     
==========================================
- Hits        17951    17878      -73     
- Misses      19714    19856     +142     
+ Partials      975      968       -7     

Files Changed	Coverage Δ
storage/src/cache/filecache/mod.rs	66.54% <100.00%> (ø)

... and 14 files with indirect coverage changes