isthmus: PostgreSqlIntegrationTest logs SQL with printf specifiers, so SLF4J discards it

[nielspardon]

PostgreSqlIntegrationTest logs the two SQL statements a result mismatch would be diagnosed from, using printf specifiers:

LOG.atDebug().log("Reference SQL:\n%s", referenceSql);
LOG.atDebug().log("Generated SQL:\n%s", generatedSql);

SLF4J substitutes {} anchors, not printf conversions, so the specifier is emitted verbatim and the argument is discarded — no exception, no warning. Against the pinned pair (slf4j 2.0.18 plus slf4j-jdk14, gradle/libs.versions.toml):

L.atInfo().log("PCT   Reference SQL:\n%s", "SELECT 1")   ->  INFO: PCT   Reference SQL:\n%s
L.atInfo().log("BRACE Reference SQL:\n{}", "SELECT 1")   ->  INFO: BRACE Reference SQL:\nSELECT 1

So anyone enabling debug logging to diff a TPC-H reference against the generated query gets two lines reading literally Reference SQL: and %s. InvalidLogMessageFormat does not catch it — it does not model the fluent atLevel().log(...) builder, and it counts %s as a placeholder, so one specifier plus one argument reads as matching.

The fix is {} in both lines. These are the only two logging calls in the repo that mix printf specifiers into a logging call; there is no inverse case of {} inside a String.format. The class is @Tag("integration") and excluded from :isthmus:test, so this only affects the separate integrationTest task, which is why it went unnoticed.

Measured on main at 944b921.