hack/analyze-memory-profiles: misc improvements
hack/analyze-memory-profiles: misc improvements

This patch adds:

 - use the creation timestamp of the profile files instead of the time
   in the output as the output time only has resolution to the minute
 - add the maximum of a series to its legend entry
 - plot the overall aggregate usage as well

Signed-off-by: Steve Kuznetsov <a7da0fca91d9933d2725d731a48cabdc9e8ffd7a@redhat.com>

dims/test-infra,dims/test-infra,kubernetes/test-infra,BenTheElder/test-infra,cjwagner/test-infra,cjwagner/test-infra,BenTheElder/test-infra,kubernetes/test-infra,michelle192837/test-infra,dims/test-infra,kubernetes/test-infra,michelle192837/test-infra,cblecker/test-infra,jessfraz/test-infra,monopole/test-infra,fejta/test-infra,cblecker/test-infra,fejta/test-infra,BenTheElder/test-infra,dims/test-infra,monopole/test-infra,michelle192837/test-infra,monopole/test-infra,cblecker/test-infra,fejta/test-infra,cjwagner/test-infra,fejta/test-infra,kubernetes/test-infra,jessfraz/test-infra,BenTheElder/test-infra,monopole/test-infra,jessfraz/test-infra,pwittrock/test-infra,dims/test-infra,michelle192837/test-infra,cjwagner/test-infra,jessfraz/test-infra,pwittrock/test-infra,pwittrock/test-infra,pwittrock/test-infra,michelle192837/test-infra,jessfraz/test-infra,BenTheElder/test-infra,monopole/test-infra,cblecker/test-infra,fejta/test-infra,kubernetes/test-infra,kubernetes/test-infra,jessfraz/test-infra,pwittrock/test-infra,dims/test-infra,cjwagner/test-infra,cblecker/test-infra,cjwagner/test-infra,fejta/test-infra,cblecker/test-infra,BenTheElder/test-infra,monopole/test-infra,michelle192837/test-infra