apollo_dashboard: add strk_to_usd oracle success and error alerts (#14703)

[matanl-starkware]

Backport of #14703 to main-v0.14.3.

Clean git cherry-pick -x of ba478333bc. No starknet_version change (V0_14_3 preserved).

Stacked on matanl/bp-14702-oracle-alert-builders — merge that first.

Generated dev_grafana_alerts.json regenerated and verified identical (no-op).

[reviewable-StarkWare]

This change is 

[cursor]

PR Summary

Low Risk
Observability-only dashboard alert definitions; no runtime gas-price or consensus logic changes.

Overview
Adds Grafana alerting for the SNIP35 STRK→USD oracle, parallel to the existing ETH→STRK oracle alerts.

New builders in l1_gas_prices.rs wire snip35_strk_usd_success_count and snip35_strk_usd_error_count through the shared oracle_success_count_alert / oracle_error_count_alert helpers (1h sum(increase), success < 1, errors > 10). Success severity uses a per-alert placeholder; errors are informational (p5 in dev JSON).

get_apollo_alerts() registers both alerts, and dev_grafana_alerts.json is updated with the corresponding rule definitions.

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