Update prometheus buckets

[zakir-hyder]

Update to 0.1, 0.2, 0.3, 0.5, 0.75, 1, 1.5, 2, 3, 5, 7, 10, 15, 20 to better capture slow requests up to 15-20 seconds while focusing on the typical range
0.1, 0.2, 0.3, 0.5, 0.75, 1, 1.5, 2, 3, 5, 7, 10, 15, 20

Why This Range?

Starts at 0.1s: our mean response times (285-548 ms) suggest most requests are above 0.1s, so smaller buckets like 0.005s are likely underutilized.
Fine-grained up to 1s: Buckets like 0.1, 0.2, 0.3, 0.5, 0.75, 1 provide good granularity where most requests fall.
Wider spacing for slower requests: 1.5, 2, 3, 5, 7, 10, 15, 20 capture the tail, ensuring requests up to 15s (or even 20s) are tracked explicitly.
Total Buckets: 14, reducing metric cardinality.

[zakir-hyder]

remove 7, 10, 15, 20 from prom bucket
Dove had issues after releasing ref https://carousell.slack.com/archives/C017WSWDT6X/p1748921073511149. based ashraful's comment https://carousell.slack.com/archives/C01F7H2DV1D/p1748949372329709?thread_ts=1748941898.905969&cid=C01F7H2DV1D i'm reducing the bucket.

dove is correct now https://carousell.slack.com/archives/C017WSWDT6X/p1752526259525309?thread_ts=1748921073.511149&cid=C017WSWDT6X