Add agent config option to set NGINX API URL #6665

Job	Run time
Component Tests	1m 10s
Unit Tests	3m 55s
Lint	58s
Build unsigned snapshot	4m 33s
Build Grafana Dashboard Example	1m 30s
Build signed snapshot	3m 52s
Performance Tests	8m 22s
Integration Tests - Official Plus Images (alpine, 3.20, r32, alpine, /nginx-plus/agent)	3m 44s
Integration Tests - Official Plus Images (debian, bookworm, r32, debian, /nginx-plus/agent)	3m 45s
Integration Tests - Official Plus Images (debian, bookworm, r31, debian, /nginx-plus/agent)	3m 29s
Integration Tests - Official OSS Images (bookworm, mainline, debian)	3m 37s
Integration Tests - Official OSS Images (alpine, stable, alpine)	3m 35s
Integration Tests - Official OSS Images (alpine, mainline, alpine)	3m 30s
Integration Tests - Official OSS Images (bookworm, stable, debian)	3m 39s
Integration Tests (ubuntu, 24.04)	4m 14s
Integration Tests (almalinux, 8)	5m 13s
Integration Tests (rockylinux, 9)	5m 15s
Integration Tests (amazonlinux, 2)	5m 54s
Integration Tests (rockylinux, 8)	5m 41s
Integration Tests (oraclelinux, 8)	6m 14s
Integration Tests (alpine, 3.21)	3m 51s
Integration Tests (debian, bullseye-slim)	4m 21s
Integration Tests (alpine, 3.20)	3m 52s
Integration Tests (oraclelinux, 9)	5m 23s
Integration Tests (debian, bookworm-slim)	4m 15s
Integration Tests (alpine, 3.22)	3m 47s
Integration Tests (alpine, 3.23)	3m 40s
Integration Tests (amazonlinux, 2023)	4m 54s
Integration Tests (almalinux, 9)	4m 29s
	2h 0m 42s

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