Use lexical-binding in many emacs-lisp tests

Use lexical-binding in many emacs-lisp tests

* test/lisp/emacs-lisp/bytecomp-tests.el:
* test/lisp/emacs-lisp/ert-x-tests.el:
* test/lisp/emacs-lisp/nadvice-tests.el:
* test/lisp/emacs-lisp/pcase-tests.el:
* test/lisp/emacs-lisp/seq-tests.el:
* test/lisp/emacs-lisp/subr-x-tests.el:
* test/lisp/emacs-lisp/text-property-search-tests.el: Use
lexical-binding.

* test/lisp/emacs-lisp/seq-tests.el (test-seq-filter)
(test-seq-remove, test-seq-count, test-seq-every-p): Silence
byte-compiler.