[dv/dvsim] Group failures per test in buckets
[dv/dvsim] Group failures per test in buckets

Within each bucket collect failures per unqualified test name.
Cap the failures shown to 5 unqualified test names and qualified
tests 2 for each.
Show the number of failures per bucket and per test.
Use a trailing backslash to separate the line and log info from the
qualified test name.

Signed-off-by: Guillermo Maturana <085716c7110d3f31793f7d964c2e5fd26da1c550@google.com>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan