Web GUI retry timer logic is incorrect

https://github.com/google/openhtf/blob/655e85df7134db7bdf8f8fdd6ff9a6bf932e7b09/openhtf/output/web_gui/src/app/shared/subscription.ts#L130
The line above means that the retry time will always be Number.MAX_VALUE. It should be the lower of the retry max value and the current retry. Additionally, subscription.spec.ts fails the following unit test https://github.com/google/openhtf/blob/655e85df7134db7bdf8f8fdd6ff9a6bf932e7b09/openhtf/output/web_gui/src/app/shared/subscription.spec.ts#L153
unless Math.max is replaced with Math.min.