Auto-indent in multi-line strings

Issue Report Checklist

[x] Searched the issues page for similar reports
[x] Read the relevant sections of the Spyder Troubleshooting Guide and followed its advice
[x] Reproduced the issue after updating with conda update spyder (or pip, if not using Anaconda)
[ ] Could not reproduce inside jupyter qtconsole (if console-related)
[ ] Tried basic troubleshooting (if a bug/error)
- [ ] Restarted Spyder
- [ ] Reset preferences with spyder --reset
- [ ] Reinstalled the latest version of Anaconda
- [ ] Tried the other applicable steps from the Troubleshooting Guide
[x] Completed the Problem Description, Steps to Reproduce and Version sections below

Problem Description

Whenever I am pressing Enter when I am between parentheses () in any multi-line string (""" """), spyder autoindents the next line and I have to press backspace repeatedly to get to the beginning of the line.

What steps reproduce the problem?

There are different cases, depending where the cursor is, when you press Enter (I marked the cursor position with ¦):

In the first line:

"""Spyder is great (¦
"""

becomes after pressing Enter

"""Spyder is great (
¦
"""

In any other line:

"""Spyder is great
Spyder is great (¦
"""

becomes after pressing Enter

"""Spyder is great.
Spyder is great (
    ¦
"""

If you already have some text after the opening parenthesis - first line:
```
"""Spyder is great (really|
"""
```
becomes after pressing Enter
```
"""Spyder is great (really
¦
"""
```

… but in every other line:

"""Spyder is great.

Spyder is great (really¦
"""

becomes after pressing Enter

"""Spyder is great.

Spyder is great (really
                 ¦
"""

With an open quotation mark (it does not matter, if it is a " or ') before the opening parenthesis, everything works like expected:
```
"""Spyder is great.

Spyder is "great (really¦
"""
```
becomes after pressing Enter
```
"""Spyder is great.

Spyder is "great (really
¦
"""
```
The same behaviour can be observed with square and curly brackets [] and {}.

What is the expected output? What do you see instead?

It would be great, if the cursor gets positioned always at same column as the beginning of the previous line.

Exceptions are, when the line starts with >>> or ....

Versions

Spyder version: 4.2.3
Python version: 3.8.5 64-bit
Qt version: Qt 5.12.9
PyQt version: PyQt5 5.12.3
Operating System name/version: Linux Mint 20.1

Dependencies

# Mandatory:
atomicwrites >=1.2.0            :  1.4.0 (OK)
chardet >=2.0.0                 :  4.0.0 (OK)
cloudpickle >=0.5.0             :  1.6.0 (OK)
diff_match_patch >=20181111     :  20200713 (OK)
intervaltree >=3.0.2            :  3.1.0 (OK)
IPython >=7.6.0                 :  7.21.0 (OK)
jedi =0.17.2                    :  0.17.2 (OK)
jsonschema >=3.2.0              :  3.2.0 (OK)
keyring >=17.0.0                :  23.0.0 (OK)
nbconvert >=4.0                 :  6.0.7 (OK)
numpydoc >=0.6.0                :  1.1.0 (OK)
parso =0.7.0                    :  0.7.0 (OK)
pexpect >=4.4.0                 :  4.6.0 (OK)
pickleshare >=0.4               :  0.7.5 (OK)
psutil >=5.3                    :  5.5.1 (OK)
pygments >=2.0                  :  2.8.1 (OK)
pylint >=1.0                    :  2.7.2 (OK)
pyls >=0.36.2;<1.0.0            :  0.36.2 (OK)
pyls_black >=0.4.6              :  0.4.6 (OK)
pyls_spyder >=0.3.2             :  0.3.2 (OK)
qdarkstyle >=2.8                :  2.8.1 (OK)
qtawesome >=0.5.7               :  1.0.2 (OK)
qtconsole >=5.0.1               :  5.0.2 (OK)
qtpy >=1.5.0                    :  1.9.0 (OK)
setuptools >=39.0.0             :  54.1.1 (OK)
sphinx >=0.6.6                  :  3.5.2 (OK)
spyder_kernels >=1.10.2;<1.11.0 :  1.10.2 (OK)
textdistance >=4.2.0            :  4.2.1 (OK)
three_merge >=0.1.1             :  0.1.1 (OK)
watchdog >=0.10.3;<2.0.0        :  1.0.2 (OK)
xdg >=0.26                      :  0.26 (OK)
zmq >=17                        :  22.0.3 (OK)

# Optional:
cython >=0.21                   :  None (NOK)
matplotlib >=2.0.0              :  3.3.4 (OK)
numpy >=1.7                     :  1.20.1 (OK)
pandas >=1.1.1                  :  1.2.3 (OK)
scipy >=0.17.0                  :  1.6.1 (OK)
sympy >=0.7.3                   :  1.7.1 (OK)

spyder-ide / spyder