test_runner: use LFC by default (#8613)

## Problem
LFC is not enabled by default in tests, but it is enabled in production.
This increases the risk of errors in the production environment, which
were not found during the routine workflow.
However, enabling LFC for all the tests may overload the disk on our
servers and increase the number of failures.
So, we try enabling  LFC in one case to evaluate the possible risk.

## Summary of changes
A new environment variable, USE_LFC is introduced. If it is set to true,
LFC is enabled by default in all the tests.
In our workflow, we enable LFC for PG17, release, x86-64, and disabled
for all other combinations.

---------

Co-authored-by: Alexey Masterov <alexeymasterov@neon.tech>
Co-authored-by: a-masterov <72613290+a-masterov@users.noreply.github.com>

scripts/ingest_regress_test_result-new-format.py

@@ -31,6 +31,7 @@ CREATE TABLE IF NOT EXISTS results (
     duration     INT NOT NULL,
     flaky        BOOLEAN NOT NULL,
     arch         arch DEFAULT 'X64',
+    lfc          BOOLEAN DEFAULT false NOT NULL,
     build_type   TEXT NOT NULL,
     pg_version   INT NOT NULL,
     run_id       BIGINT NOT NULL,
@@ -54,6 +55,7 @@ class Row:
     duration: int
     flaky: bool
     arch: str
+    lfc: bool
     build_type: str
     pg_version: int
     run_id: int
@@ -132,6 +134,7 @@ def ingest_test_result(
             if p["name"].startswith("__")
         }
         arch = parameters.get("arch", "UNKNOWN").strip("'")
+        lfc = parameters.get("lfc", "False") == "True"
 
         build_type, pg_version, unparametrized_name = parse_test_name(test["name"])
         labels = {label["name"]: label["value"] for label in test["labels"]}
@@ -145,6 +148,7 @@ def ingest_test_result(
             duration=test["time"]["duration"],
             flaky=test["flaky"] or test["retriesStatusChange"],
             arch=arch,
+            lfc=lfc,
             build_type=build_type,
             pg_version=pg_version,
             run_id=run_id,