fix: remove false-positive billing error rewrite on normal assistant text (openclaw#17834) thanks @niceysam

Verified:
- pnpm install --frozen-lockfile
- pnpm build
- pnpm check
- pnpm test:macmini

Co-authored-by: niceysam <256747835+niceysam@users.noreply.github.com>
Co-authored-by: Tak Hoffman <781889+Takhoffman@users.noreply.github.com>

src/agents/pi-embedded-helpers/errors.ts

@@ -244,18 +244,6 @@ function shouldRewriteContextOverflowText(raw: string): boolean {
   );
 }
 
-function shouldRewriteBillingText(raw: string): boolean {
-  if (!isBillingErrorMessage(raw)) {
-    return false;
-  }
-  return (
-    isRawApiErrorPayload(raw) ||
-    isLikelyHttpErrorText(raw) ||
-    ERROR_PREFIX_RE.test(raw) ||
-    BILLING_ERROR_HEAD_RE.test(raw)
-  );
-}
-
 type ErrorPayload = Record<string, unknown>;
 
 function isErrorPayloadObject(payload: unknown): payload is ErrorPayload {
@@ -552,13 +540,6 @@ export function sanitizeUserFacingText(text: string, opts?: { errorContext?: boo
     }
   }
 
-  // Preserve legacy behavior for explicit billing-head text outside known
-  // error contexts (e.g., "billing: please upgrade your plan"), while
-  // keeping conversational billing mentions untouched.
-  if (shouldRewriteBillingText(trimmed)) {
-    return BILLING_ERROR_USER_MESSAGE;
-  }
-
   // Strip leading blank lines (including whitespace-only lines) without clobbering indentation on
   // the first content line (e.g. markdown/code blocks).
   const withoutLeadingEmptyLines = stripped.replace(/^(?:[ \t]*\r?\n)+/, "");