Don't count added labels when initializing slice (#10756)
Don't count added labels when initializing slice (#10756)

This was added in #10749 but based on feedback it might be over-allocating so worth removing.

Signed-off-by: Łukasz Mierzwa <1cf2a1b97eca6408a942167bdf2254654cde5131@gmail.com>
prometheus/prometheus,prometheus/prometheus,prometheus/prometheus,prometheus/prometheus,prometheus/prometheus