Add fail-close support for fetching expectations by adding error handling & surfacing the errors being swallowed by grp.Wait().

Signed-off-by: David-Jaeyoon-Lee <davjlee@google.com>

Remove the starting hyphen from the
crash-on-failure-fetching-expectations flag

Signed-off-by: David-Jaeyoon-Lee <davjlee@google.com>

and add unit tests
Fix comments and return error in trackConfigAndSyncSets. Add unit tests
for each track method & each wait in Run method.

Signed-off-by: David-Jaeyoon-Lee <davjlee@google.com>

in test

Signed-off-by: David-Jaeyoon-Lee <davjlee@google.com>

Change errgroup logic such that we instead use waitgroups and errchannels.
This is that we remove the idea of shared fate between each
tracking/subtracking threads. Removes complexity of figuring out what the
errgroups are doing as well as complicated logic with shared fate between
tracking threads and singlerunners

Signed-off-by: David-Jaeyoon-Lee <davjlee@google.com>

Signed-off-by: David-Jaeyoon-Lee <davjlee@google.com>

Signed-off-by: David-Jaeyoon-Lee <davjlee@google.com>