Plugin manager search inadvertently upgrades all plugns

[kgjenkins]

What is the bug or the crash?

When typing a search query in the QGIS Plugin Manager, if the user presses the "Enter" key, the "Upgrade All" button gets activated and QGIS starts upgrading all the installed plugins, even though the user was just trying to search for plugins.

Steps to reproduce the issue

1. Open the QGIS Plugin Manager.
2. Type something in the search box
3. Press the "Enter" key
4. Wait while all your upgradeable plugins get upgraded...

https://user-images.githubusercontent.com/3355358/190220289-6ae82be8-d5b4-46d1-b0b7-7ff452c3707d.mp4

Versions

QGIS version 3.26.3-Buenos Aires QGIS code revision 65e4edfdada Qt version 5.15.3 Python version 3.9.5 GDAL/OGR version 3.5.1 PROJ version 9.1.0 EPSG Registry database version v10.074 (2022-08-01) GEOS version 3.10.3-CAPI-1.16.1 SQLite version 3.38.1 PDAL version 2.4.3 PostgreSQL client version unknown SpatiaLite version 5.0.1 QWT version 6.1.6 QScintilla2 version 2.13.1 OS version Windows 10 Version 2009

Active Python plugins Discovery 2.5.7 ee_plugin 0.0.5 latlontools 3.6.4 LayerBoard 1.0.1 mmqgis 2021.9.10 nys-geocoder 0.1 plugin_reloader 0.9.1 processing_saga_nextgen 0.0.7 processing_wbt 1.3.1 qgis2web 3.16.0-color-svg QGIS3-getWKT 1.4 qgis_preview_mode_plugin 0.1.0 QNEAT3 1.0.4 quick_map_services 0.19.29 RasterAttributeTable 1.1 SRTM-Downloader 3.1.17 StreetView 3.2 ThRasE 22.3.3a timemanager 3.6 valuetool 3.0.15 zoom_level 0.2.0 db_manager 0.1.20 processing 2.12.99 qgis_stac 1.1.1 QuickOSM 2.1.1

Supported QGIS version

• [X] I'm running a supported QGIS version according to the roadmap.

New profile

• [ ] I tried with a new QGIS profile

Additional context

I didn't try with a new profile, because the undesired behavior depends on having an upgradable plugin installed.

[uclaros]

Indeed, focus should be on Install Plugin button by default instead