roachtest: add 1M table introspection benchmark variant

[rafiss]

Add a new variant of the large-schema-benchmark roachtest that creates 1 million tables and benchmarks introspection query performance. Unlike the existing benchmark variants, this test:

• Uses minimal data import (warehouses=1) instead of full TPCC data
• Skips the TPCC workload and runs only ORM introspection queries
• Tests at a much larger scale (1M tables vs max 40K)
• Single-region only configuration
• 48-hour timeout to accommodate the larger scale

This serves as a smoke test to determine how introspection queries perform with 1 million tables, as part of our efforts to improve introspection query performance.

Resolves: #159557
Epic: CRDB-54999

Release note: None

[cockroach-teamcity]

This change is 

[cockroach-teamcity]

⚪ Sysbench [SQL, 3node, oltp_read_write]

Metric	Old Commit	New Commit	Delta	Note
⚪ sec/op	10.80m ±1%	10.84m ±1%	~	p=0.486 n=15
⚪ allocs/op	8.020k ±0%	8.042k ±2%	~	p=0.442 n=15

Reproduce

benchdiff binaries:

mkdir -p benchdiff/19a2374/bin/1058449141
gcloud storage cp gs://cockroach-microbench-ci/builds/19a23749f4e265442c58d8d76bb5a40775fc20c2/bin/pkg_sql_tests benchdiff/19a2374/bin/1058449141/cockroachdb_cockroach_pkg_sql_tests
chmod +x benchdiff/19a2374/bin/1058449141/cockroachdb_cockroach_pkg_sql_tests
mkdir -p benchdiff/a214566/bin/1058449141
gcloud storage cp gs://cockroach-microbench-ci/builds/a214566cc04655e11ff731c95e08c994dc8c64e9/bin/pkg_sql_tests benchdiff/a214566/bin/1058449141/cockroachdb_cockroach_pkg_sql_tests
chmod +x benchdiff/a214566/bin/1058449141/cockroachdb_cockroach_pkg_sql_tests

benchdiff command:

benchdiff --run=^BenchmarkSysbench/SQL/3node/oltp_read_write$ --old=a214566 --new=19a2374 ./pkg/sql/tests

⚪ Sysbench [KV, 3node, oltp_read_only]

Metric	Old Commit	New Commit	Delta	Note
⚪ sec/op	3.571m ±2%	3.609m ±1%	~	p=0.026 n=15
⚪ allocs/op	2.084k ±1%	2.064k ±0%	~	p=0.071 n=15

Reproduce

benchdiff binaries:

mkdir -p benchdiff/19a2374/bin/1058449141
gcloud storage cp gs://cockroach-microbench-ci/builds/19a23749f4e265442c58d8d76bb5a40775fc20c2/bin/pkg_sql_tests benchdiff/19a2374/bin/1058449141/cockroachdb_cockroach_pkg_sql_tests
chmod +x benchdiff/19a2374/bin/1058449141/cockroachdb_cockroach_pkg_sql_tests
mkdir -p benchdiff/a214566/bin/1058449141
gcloud storage cp gs://cockroach-microbench-ci/builds/a214566cc04655e11ff731c95e08c994dc8c64e9/bin/pkg_sql_tests benchdiff/a214566/bin/1058449141/cockroachdb_cockroach_pkg_sql_tests
chmod +x benchdiff/a214566/bin/1058449141/cockroachdb_cockroach_pkg_sql_tests

benchdiff command:

benchdiff --run=^BenchmarkSysbench/KV/3node/oltp_read_only$ --old=a214566 --new=19a2374 ./pkg/sql/tests

🔴 Sysbench [KV, 3node, oltp_write_only]

Metric	Old Commit	New Commit	Delta	Note
🔴 sec/op	3.927m ±0%	3.971m ±1%	+1.13%	p=0.000 n=15
⚪ allocs/op	4.158k ±0%	4.159k ±0%	~	p=0.288 n=15

Reproduce

benchdiff binaries:

mkdir -p benchdiff/19a2374/bin/1058449141
gcloud storage cp gs://cockroach-microbench-ci/builds/19a23749f4e265442c58d8d76bb5a40775fc20c2/bin/pkg_sql_tests benchdiff/19a2374/bin/1058449141/cockroachdb_cockroach_pkg_sql_tests
chmod +x benchdiff/19a2374/bin/1058449141/cockroachdb_cockroach_pkg_sql_tests
mkdir -p benchdiff/a214566/bin/1058449141
gcloud storage cp gs://cockroach-microbench-ci/builds/a214566cc04655e11ff731c95e08c994dc8c64e9/bin/pkg_sql_tests benchdiff/a214566/bin/1058449141/cockroachdb_cockroach_pkg_sql_tests
chmod +x benchdiff/a214566/bin/1058449141/cockroachdb_cockroach_pkg_sql_tests

benchdiff command:

benchdiff --run=^BenchmarkSysbench/KV/3node/oltp_write_only$ --old=a214566 --new=19a2374 ./pkg/sql/tests

Artifacts

download:

mkdir -p new
gcloud storage cp gs://cockroach-microbench-ci/artifacts/19a23749f4e265442c58d8d76bb5a40775fc20c2/20772861632-1/\* new/
mkdir -p old
gcloud storage cp gs://cockroach-microbench-ci/artifacts/a214566cc04655e11ff731c95e08c994dc8c64e9/20772861632-1/\* old/

built with commit: 19a23749f4e265442c58d8d76bb5a40775fc20c2