Build: fix failing tests on master (#10890)

This updates some failing tests to account for an error message change in the `ajv` dependency.

tests/lib/config/config-validator.js

@@ -342,7 +342,7 @@ describe("Validator", () => {
             it("should throw if override has an empty files array", () => {
                 const fn = validator.validate.bind(null, { overrides: [{ files: [] }] }, "tests", ruleMapper, linter.environments);
 
-                assert.throws(fn, "ESLint configuration in tests is invalid:\n\t- Property \"overrides[0].files\" is the wrong type (expected string but got `[]`).\n\t- \"overrides[0].files\" should NOT have less than 1 items. Value: [].\n\t- \"overrides[0].files\" should match exactly one schema in oneOf. Value: [].\n");
+                assert.throws(fn, "ESLint configuration in tests is invalid:\n\t- Property \"overrides[0].files\" is the wrong type (expected string but got `[]`).\n\t- \"overrides[0].files\" should NOT have fewer than 1 items. Value: [].\n\t- \"overrides[0].files\" should match exactly one schema in oneOf. Value: [].\n");
             });
 
             it("should throw if override has nested overrides", () => {

tests/lib/testers/rule-tester.js

@@ -640,7 +640,7 @@ describe("RuleTester", () => {
                     { code: "var answer = 6 * 7;", options: ["bar"], errors: [{ message: "Expected nothing." }] }
                 ]
             });
-        }, "Schema for rule no-invalid-schema is invalid:,\titems: should be object\n\titems[0].enum: should NOT have less than 1 items\n\titems: should match some schema in anyOf");
+        }, "Schema for rule no-invalid-schema is invalid:,\titems: should be object\n\titems[0].enum: should NOT have fewer than 1 items\n\titems: should match some schema in anyOf");
 
     });