[BUG] Upgrade elasticsearch-oss to 7.9.1 & ODFE to the latest version (1.10.1)

[rafzei]

Describe the bug
During testing I found this regression bug in Elasticsearch v7.8.0. It was fixed in ES 7.8.1, see PR.

To Reproduce
Steps to reproduce the behavior:
It's not possible to upgrade only Elasticsearch without Open Distro for Elasticsearch, for example:

apt-get install opendistro-alerting
The following packages have unmet dependencies:\n opendistro-alerting : Depends: elasticsearch-oss (= 7.8.0) but 7.8.1 is to be installed
E: Unable to correct problems, you have held broken packages.

Expected behavior
Successful installation.

Config files
No.

OS (please complete the following information):

• OS: All

Cloud Environment (please complete the following information):

• Cloud Provider: All

Additional context
ODFE just released new version (1.10.1), see here.

Originally posted by @to-bar in #1140 (comment)

[mkyc]

This task fixes issue introduced in #1140

[rafzei]

On block because of #1741

[to-bar]

With PR #1718 we have introduced Jinja template for jvm.options file. This file defines JVM heap size (Xmx). The default is 1 GB but Elasticsearch doc says:

When moving to production, it is important to configure heap size to ensure that Elasticsearch has enough heap available.

So it is very likely that one could increase the JVM heap size. But for epicli upgrade we do not support defining custom values for new configuration settings. The setting specification.jvm_options has been introduced in v0.8.0rc1.
Current code (for upgrades) always uses the default value, i.e 1 GB (see PR #1763), so any customized value is overwritten during the upgrade. To solve this issue we can try to get the existing setting from remote host (from jvm.options file) to preserve the custom value instead of overwriting it with the default.

More info: https://www.elastic.co/guide/en/elasticsearch/reference/7.9/heap-size.html

This JVM heap size issue can be solved in separate PR.

[rafzei]

@przemyslavic @to-bar Was it tested? If so, please move it to the correct column.

[przemyslavic]

Tested mainly by @to-bar.