Most of the time it exits, e.g. when it is per-container and use on each
object PUT. Bbolt implementation first tries to create bucket and then
returns it if it exists. Create operation uses cursor and thus is not
very lightweight, we can avoid it.
```
goos: linux
goarch: amd64
pkg: git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase
cpu: 11th Gen Intel(R) Core(TM) i5-1135G7 @ 2.40GHz
│ old │ new │
│ sec/op │ sec/op vs base │
Put/parallel-8 174.4µ ± 3% 163.3µ ± 3% -6.39% (p=0.000 n=10)
Put/sequential-8 263.3µ ± 2% 259.0µ ± 1% -1.64% (p=0.000 n=10)
geomean 214.3µ 205.6µ -4.05%
│ old │ new │
│ B/op │ B/op vs base │
Put/parallel-8 275.3Ki ± 3% 281.1Ki ± 4% ~ (p=0.063 n=10)
Put/sequential-8 413.0Ki ± 2% 426.6Ki ± 2% +3.29% (p=0.003 n=10)
geomean 337.2Ki 346.3Ki +2.70%
│ old │ new │
│ allocs/op │ allocs/op vs base │
Put/parallel-8 678.0 ± 1% 524.5 ± 2% -22.64% (p=0.000 n=10)
Put/sequential-8 1.329k ± 0% 1.183k ± 0% -10.91% (p=0.000 n=10)
geomean 949.1 787.9 -16.98%
```
Signed-off-by: Evgenii Stratonikov <e.stratonikov@yadro.com>
