test: Use RSA 4096 algorithm for JWT load test (#4118)

Until now we had a load test with 50k unique JWTs signed with symmetric key.
This commit adds a new load test with 10k JWTs signed with RSA 4096.

Existing -k jwt parameter was changed to -k jwt-hs-50k.
New test is run with -k jwt-rsa-10k parameter.

Additionally a new parameter --jwtcache=off was added to turn off JWT caching in the above load tests.

nix/tools/generate_targets_rsa.py

@@ -0,0 +1,68 @@
+# generates a file to be used by the vegeta load testing tool
+# It runs TOTAL_TARGETS amount of requests with
+# TOTAL_JWTS amount of JWTs randomly spread among them
+import time
+import argparse
+import sys
+import random
+import jwt
+import jwcrypto.jwk as jwk
+
+URL = "http://postgrest"
+TOTAL_JWTS = 1000
+TOTAL_TARGETS = 50000  # tuned by hand to reduce result variance
+
+key = jwk.JWK.generate(kty="RSA", size=4096)
+
+private_key = jwt.algorithms.RSAAlgorithm.from_jwk(key.export_private())
+public_key = key.export_public()
+
+
+def generate_jwt() -> str:
+    """Generate an RS256 JWT"""
+    now = int(time.time())
+    payload = {
+        "sub": f"user_{random.getrandbits(32)}",
+        "iat": now,
+        "role": "postgrest_test_author",
+    }
+
+    return jwt.encode(payload, private_key, "RS256")
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Generate Vegeta targets with unique JWTs"
+    )
+    parser.add_argument(
+        "output",
+        help="Path to write the generated targets file",
+    )
+    parser.add_argument("jwk", help="Path to write the generated JWK")
+    args = parser.parse_args()
+
+    tokens = [generate_jwt() for _ in range(TOTAL_JWTS)]
+    lines = []
+    start_time = time.time()
+
+    for i in range(TOTAL_TARGETS):
+        token = random.choice(tokens)
+        lines.append(f"OPTIONS {URL}/authors_only")
+        lines.append(f"Authorization: Bearer {token}")
+        lines.append("")  # blank line to separate requests
+
+    try:
+        with open(args.jwk, "w") as jwk, open(args.output, "w") as f:
+            jwk.write(public_key)
+            f.write("\n".join(lines))
+    except IOError as e:
+        print(f"Error writing to {args.output}: {e}", file=sys.stderr)
+        sys.exit(1)
+
+    elapsed = time.time() - start_time
+    print(f"Created {TOTAL_TARGETS} targets with unique JWTs", end=" ")
+    print(f"in {args.output} ({elapsed:.2f}s)")
+
+
+if __name__ == "__main__":
+    main()