fix seamless caching

[atolopko-czi]

https://app.zenhub.com/workspaces/single-cell-5e2a191dad828d52cc78b028/issues/chanzuckerberg/single-cell-explorer/166

Reviewers

Functional:
@Bento007

Readability:
@blrnw3

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Changes

Follow-up fix to #177. In addition to setting cache control headers (to avoid caching of result), we also needed to not cache the data in the server's own memory cache. Note that this server caching logic is being removed entirely in the Cache Redesign epic, but this PR removes it in one place to specifically fix the Seamless collection/dataset dropdown problems.

[codecov]

Codecov Report

Merging #191 (9d47488) into main (4b1efff) will decrease coverage by 0.00%.
The diff coverage is 90.90%.

@@            Coverage Diff             @@
##             main     #191      +/-   ##
==========================================
- Coverage   71.71%   71.71%   -0.01%     
==========================================
  Files         126      126              
  Lines       10098    10096       -2     
==========================================
- Hits         7242     7240       -2     
  Misses       2856     2856              

Flag	Coverage Δ
frontend	71.71% <90.90%> (-0.01%)	⬇️
javascript	71.71% <90.90%> (-0.01%)	⬇️
unitTest	71.71% <90.90%> (-0.01%)	⬇️

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Impacted Files	Coverage Δ
server/data_common/dataset_metadata.py	91.66% <90.90%> (-0.12%)	⬇️
data_common/dataset_metadata.py	91.66% <0.00%> (-0.12%)	⬇️

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