[bug fix] Fix check_synapse_cache_size function; allow file size to be float

[linglp]

Context

We encountered this error on AWS side (see Jira ticket here) This error was first caught by running schematic profiler, but it is now affecting a lot of endpoints, including manifest/generate, model/submit, /storage/project/datasets and so on on dev instance. The same bug also appears in staging and prod. The only reason that we are not receiving reports about this error from staging/prod is most likely because the cache size has not yet reached "GB" level

Problem

convert_gb_to_bytes has wrong typing, and this line: size_in_gb = float(size.rstrip("G")) was changed to size_in_gb = int(size.rstrip("G")) which caused the problem. Test also didn't catch this error because it was testing situations where cache size is XXKB, but not when cache size is XXGB.

Solution

1. I removed convert_gb_to_bytes function from the code base. The function was doing a simple calculation that I think we don't need a function to do it. This also resolve the "wrong typing" issue of the function since this function no longer exists.
2. The previous test_check_synapse_cache_size function creates a small test file to test check_synapse_cache_size. This means that the test was only testing when the cache size is "KB". I updated the test so that test files with various sizes (KB, MB, GB) are all tested.

Test

1. Make sure all the current tests are working on GH.
2. I ran schematic profiler while monitoring AWS logs. I could see purging cache is working:

3) Make sure all the tests are returning 200 on schematic profiler: https://www.synapse.org/#!Synapse:syn51385540/tables/query/eyJzcWwiOiJTRUxFQ1QgKiBGUk9NIHN5bjUxMzg1NTQwIiwgImluY2x1ZGVFbnRpdHlFdGFnIjp0cnVlLCAib2Zmc2V0Ijo1NzUsICJsaW1pdCI6MjV9

[mialy-defelice]

@linglp can you put the ticket number in the branch name so its tracked?

[sonarqubecloud]

Quality Gate passed

Issues
2 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
0.0% Duplication on New Code

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