Improvements to avoid leader election timeout

[MartinWeindel]

What this PR does / why we need it:
On busy seeds the DNS controller manager loses its lease sporadically because of lease timeout.
To mitigate this behaviour, several changes have been applied:

• enlarge default minAllow value in VPA from 20m to 50 m CPU
• longer default lease duration (from 15s to 30s)
• restrict GOMAXPROCS by importing go.uber.org/automaxprocs
• using global shared informer for secrets (was not used because of code ordering and namespaced informers have been created instead)

Further future usage, a command line flag --enableProfiling has added to enable the profiling endpoints optionally on the server http port.

Special notes for your reviewer:

Release note:

Improvements to avoid leader election timeout: longer default lease duration, higher CPU minimum