OBS-486: remove legacy elasticsearch

[relud]

No description provided.

[willkg]

We need to remove some other lines:

$ rg LEGACY_ELASTICSEARCH
bin/waitfor_services.sh
16:waitfor --verbose "${LEGACY_ELASTICSEARCH_URL}"

bin/test.sh
22:LEGACY_ELASTICSEARCH_URL="${LEGACY_ELASTICSEARCH_URL:-}"

[willkg]

Nevermind--you got them!

[willkg]

I went through local dev environment workflows: build, setup, run, test, etc. I also searched across the codebase for some things that were removed.

Some docs we should update:

socorro/external/es/crashstorage.py
292:    # have been tested with Elasticsearch 1.4.

docs/crashstorage.rst
70:Socorro currently requires Elasticsearch version 1.4.
241:See `Elasticsearch 1.4 mapping documentation
242:<https://www.elastic.co/guide/en/elasticsearch/reference/1.4/mapping.html>`_.

webapp/crashstats/documentation/jinja2/docs/supersearch/home.html
274:          <td>The field value matches the given regular expression. The accepted syntax is described in the <a href="https://www.elastic.co/guide/en/elasticsearch/reference/1.4/query-dsl-regexp-query.html#regexp-syntax">Elasticsearch documentation</a>.</td>

webapp/crashstats/documentation/jinja2/docs/supersearch/examples.html
131:      href="https://www.elastic.co/guide/en/elasticsearch/reference/1.4/query-dsl-regexp-query.html#regexp-syntax">Elasticsearch

Otherwise, this looks good plus it's soooo nice that building and running tests is much faster now.

r+wc