[AUDIT] Run knip over twenty-server (#21159)

# Introduction
Run [knip](https://knip.dev/) over twenty-server
Used config:
```json
{
  "$schema": "https://unpkg.com/knip@5/schema.json",
  "workspaces": {
    "packages/twenty-server": {
      "entry": [
        "src/main.ts",
        "src/command/command.ts",
        "src/queue-worker/queue-worker.ts",
        "src/database/scripts/setup-db.ts",
        "src/database/scripts/truncate-db.ts",
        "src/database/clickHouse/migrations/run-migrations.ts",
        "src/database/clickHouse/seeds/run-seeds.ts",
        "src/instrument.ts",
        "lingui.config.ts",
        "test/integration/graphql/codegen/index.ts",
        "test/integration/utils/setup-test.ts",
        "test/integration/utils/teardown-test.ts",
        "scripts/**/*.ts",
        "**/*.spec.ts",
        "**/*.integration-spec.ts"
      ],
      "project": ["src/**/*.ts", "test/**/*.ts", "scripts/**/*.ts"],
      "ignore": [
        "src/database/typeorm/**/migrations/**",
        "src/database/typeorm/**/*.entity.ts",
        "**/*.workspace-entity.ts",
        "**/logic-function-resource/constants/seed-project/**"
      ],
      "ignoreDependencies": ["@types/psl", "@types/aws-lambda"],
      "ignoreBinaries": ["nest", "lingui", "typeorm"]
    }
  }
}
```

packages/twenty-server/src/engine/core-modules/billing/constants/billing-workflow-execution-error-message.constant.ts

@@ -1,2 +0,0 @@
-export const BILLING_WORKFLOW_EXECUTION_ERROR_MESSAGE =
-  'No remaining credits to execute workflow. Please check your subscription.';

packages/twenty-server/src/engine/core-modules/billing/dtos/billing-price.dto.ts

@@ -1,20 +0,0 @@
-/* @license Enterprise */
-
-import { Field, ObjectType } from '@nestjs/graphql';
-
-import { SubscriptionInterval } from 'src/engine/core-modules/billing/enums/billing-subscription-interval.enum';
-
-@ObjectType('BillingPrice')
-export class BillingPriceDTO {
-  @Field(() => Number)
-  upTo: number;
-
-  @Field(() => Number)
-  amount: number;
-
-  @Field(() => String)
-  stripePriceId: string;
-
-  @Field(() => SubscriptionInterval)
-  recurringInterval: SubscriptionInterval;
-}

packages/twenty-server/src/engine/core-modules/billing/dtos/inputs/billing-product.input.ts

@@ -1,15 +0,0 @@
-/* @license Enterprise */
-
-import { ArgsType, Field } from '@nestjs/graphql';
-
-import { IsNotEmpty, IsString } from 'class-validator';
-
-import { AvailableProduct } from 'src/engine/core-modules/billing/enums/billing-available-product.enum';
-
-@ArgsType()
-export class BillingProductInput {
-  @Field(() => String)
-  @IsString()
-  @IsNotEmpty()
-  product: AvailableProduct;
-}

packages/twenty-server/src/engine/core-modules/billing/enums/billing-available-product.enum.ts

@@ -1,5 +0,0 @@
-/* @license Enterprise */
-
-export enum AvailableProduct {
-  BasePlan = 'base-plan',
-}

packages/twenty-server/src/engine/core-modules/billing/utils/get-opposite-interval.ts

@@ -1,14 +0,0 @@
-import { SubscriptionInterval } from 'src/engine/core-modules/billing/enums/billing-subscription-interval.enum';
-import {
-  BillingException,
-  BillingExceptionCode,
-} from 'src/engine/core-modules/billing/billing.exception';
-
-export const getOppositeInterval = (interval: SubscriptionInterval) => {
-  if (interval === SubscriptionInterval.Month) return SubscriptionInterval.Year;
-  if (interval === SubscriptionInterval.Year) return SubscriptionInterval.Month;
-  throw new BillingException(
-    `Interval invalid`,
-    BillingExceptionCode.BILLING_SUBSCRIPTION_INTERVAL_INVALID,
-  );
-};

packages/twenty-server/src/engine/core-modules/billing/utils/get-opposite-plan.ts

@@ -1,14 +0,0 @@
-import {
-  BillingException,
-  BillingExceptionCode,
-} from 'src/engine/core-modules/billing/billing.exception';
-import { BillingPlanKey } from 'src/engine/core-modules/billing/enums/billing-plan-key.enum';
-
-export const getOppositePlan = (plan: BillingPlanKey) => {
-  if (plan === BillingPlanKey.PRO) return BillingPlanKey.ENTERPRISE;
-  if (plan === BillingPlanKey.ENTERPRISE) return BillingPlanKey.PRO;
-  throw new BillingException(
-    `Plan invalid`,
-    BillingExceptionCode.BILLING_PLAN_NOT_FOUND,
-  );
-};

packages/twenty-server/src/engine/core-modules/billing/utils/is-subscription-incomplete-onboarding-status.util.ts

@@ -1,5 +0,0 @@
-export const isSubscriptionIncompleteOnboardingStatus = (
-  hasAnySubscription: boolean,
-) => {
-  return !hasAnySubscription;
-};