Remove unused error_node_analysis integration test

The test never asserted anything (pure println! diagnostics) and read
a personal fixture path (~/today/categorical-predictors.qmd) that only
existed on its original author's machine, so it silently skipped for
everyone else. It also crashed on Windows shells without a HOME env
var, since the unwrap ran before the file-existence skip check.

Git history shows it was swept into a bulk "make tests pass" commit as
a one-off diagnostic script, then mechanically carried into the
permanent integration-test suite by the later test-consolidation
refactor without re-evaluation.

Author: cderv

crates/pampa/tests/integration/error_node_analysis.rs

@@ -12,7 +12,6 @@
 
 pub mod attribution_html_coalescing_test;
 pub mod attribution_json_wire_test;
-pub mod error_node_analysis;
 pub mod incremental_writer_investigation;
 pub mod incremental_writer_tests;
 pub mod inline_span_investigation;