Fix Histogram widget when there is just one row of data

[moicalcob]

Description

Shortcut: (https://app.shortcut.com/cartoteam/story/292405/ac-7xhfwyml-carto-3-histogram-widget-does-not-render-when-same-number-in-all-of-column)

When we're showing just one row of data into a Histogram widget, we were not showing any bar into the widget due to how the Apache E-charts config was generated. With this PR we'll start checking if we just have one row of data to generate the proper options for the widget.

Type of change

• Fix

Acceptance

1. Add a Histogram widget with just one row of data
2. Check that the row is shown in the widget

Acceptance in CARTO 3

1. Create a map with a query like the following one:

SELECT 1 as _num, * FROM `cartodb-gcp-solutions-eng-team.tomas_data.lavazza_here`

2. Add a histogram widget using the _num column
3. Check that the widget is shown correctly

Basic checklist

• Good PR name
• Shortcut link
• Changelog entry
• Just one issue per PR
• GitHub labels
• Proper status & reviewers
• Tests
• Documentation

[shortcut-integration]

This pull request has been linked to Shortcut Story #292405: [ac_7xhfwyml] CARTO 3 Histogram Widget Does Not Render when Same Number in all of Column.

[coveralls]

Pull Request Test Coverage Report for Build 4799931815

• 3 of 3 (100.0%) changed or added relevant lines in 1 file are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.06%) to 71.281%

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Totals
Change from base Build 4797420017:	-0.06%
Covered Lines:	1951
Relevant Lines:	2515

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💛 - Coveralls

[VictorVelarde]

Hi, why 10 value here?

[VictorVelarde]

Thx @moicalcob, we'll ship it in next 2.0.2, this week