Backups on Windows are failing due to boltdb issue

From community slack:

```
I am unable to backup data:
PS C:\Temp\influxbackup> influx backup .
2021/12/21 09:52:07 INFO: Downloading legacy KV snapshot
2021/12/21 09:52:07 INFO: Extracting bucket manifest from legacy KV snapshot
Error: failed to backup metadata: failed to extract bucket metadata from downloaded KV snapshot: unable to open boltdb:
CreateFileMapping: Not enough memory resources are available to process this command.
No differences specifying organization, bucket and token. Influx CLI is configured correctly as other commands work fine.
```

See also underlying boltdb issue: https://github.com/etcd-io/bbolt/issues/252
And https://github.com/influxdata/influx-cli/pull/183#issuecomment-876680455

Looks like we skipped a test on Windows and now its biting us. No movement on the upstream issue since Nov 2020 so we're going to have to find a workaround or fix the upstream I think.

Start by reproducing the `influx backup` failure on Windows and read the linked bbolt issue and influx-cli PR #183 discussion. Investigate the skipped Windows test and the metadata extraction path, then determine whether a workaround or upstream fix is needed. Done means Windows backups complete successfully and the regression is covered by a test.

Written by the indexing model from the issue text.