Prefer `t.true(x)` over `t.is(x, true)`

[jonahsnider]

Inspired by https://github.com/sindresorhus/ts-extras/pull/8#discussion_r740023376

Bad:

t.is(x, true);
t.is(x, false);

Good:

t.true(x);
t.false(x);

[sindresorhus]

This should be fixed in the https://github.com/avajs/eslint-plugin-ava/blob/main/docs/rules/use-true-false.md rule.