fix(utils): change default maxBuffer limit to 10MB (#7209)

lib/manager/bundler/__snapshots__/artifacts.spec.ts.snap

lib/manager/cargo/__snapshots__/artifacts.spec.ts.snap

lib/manager/cocoapods/__snapshots__/artifacts.spec.ts.snap

lib/manager/composer/__snapshots__/artifacts.spec.ts.snap

lib/manager/gomod/__snapshots__/artifacts.spec.ts.snap

...nager/gradle-wrapper/__snapshots__/artifacts.spec.ts.snap

lib/manager/gradle/__snapshots__/index.spec.ts.snap

lib/manager/mix/__snapshots__/artifacts.spec.ts.snap

lib/manager/npm/post-update/__snapshots__/lerna.spec.ts.snap

lib/manager/npm/post-update/__snapshots__/npm.spec.ts.snap

lib/manager/npm/post-update/__snapshots__/pnpm.spec.ts.snap

lib/manager/npm/post-update/__snapshots__/yarn.spec.ts.snap

lib/manager/pip_setup/__snapshots__/extract.spec.ts.snap

lib/manager/pip_setup/__snapshots__/index.spec.ts.snap

lib/manager/pipenv/__snapshots__/artifacts.spec.ts.snap

lib/manager/poetry/__snapshots__/artifacts.spec.ts.snap

lib/util/exec/exec.spec.ts

lib/util/exec/index.ts