EGL: Relax test skip conditions for a few colorspace ImageTests

Relax test skip conditions for the following colorspace
ImageTests -

- SourceRenderbufferTargetTexture_Colorspace
- SourceRenderbufferTargetTextureExternal_Colorspace
- SourceRenderbufferTargetTextureExternalESSL3_Colorspace

For these tests, it is sufficient to check for support of
EGL_EXT_image_gl_colorspace extension

Bug: angleproject:3756
Tests: angle_end2end_tests --gtest_filter=ImageTest.SourceRenderbufferTargetTexture*_Colorspace*
Change-Id: I123fb14fc79e8f949a903b7586a0badf54297cfa
Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/2144549
Commit-Queue: Courtney Goeltzenleuchter <courtneygo@google.com>
Reviewed-by: Courtney Goeltzenleuchter <courtneygo@google.com>

Author: Mohan Maiya

src/tests/gl_tests/ImageTest.cpp

@@ -1681,7 +1681,6 @@ TEST_P(ImageTest, SourceRenderbufferTargetTexture)
 
 TEST_P(ImageTest, SourceRenderbufferTargetTexture_Colorspace)
 {
-    ANGLE_SKIP_TEST_IF(getClientMajorVersion() < 3 && !IsGLExtensionEnabled("GL_EXT_sRGB"));
     ANGLE_SKIP_TEST_IF(!hasImageGLColorspaceExt());
     SourceRenderbufferTargetTexture_helper(kColorspaceAttribs);
 }
@@ -1719,7 +1718,6 @@ TEST_P(ImageTest, SourceRenderbufferTargetTextureExternal)
 
 TEST_P(ImageTest, SourceRenderbufferTargetTextureExternal_Colorspace)
 {
-    ANGLE_SKIP_TEST_IF(getClientMajorVersion() < 3 && !IsGLExtensionEnabled("GL_EXT_sRGB"));
     ANGLE_SKIP_TEST_IF(!hasImageGLColorspaceExt());
     SourceRenderbufferTargetTextureExternal_helper(kColorspaceAttribs);
 }
@@ -1760,7 +1758,6 @@ TEST_P(ImageTestES3, SourceRenderbufferTargetTextureExternalESSL3)
 
 TEST_P(ImageTestES3, SourceRenderbufferTargetTextureExternalESSL3_Colorspace)
 {
-    ANGLE_SKIP_TEST_IF(getClientMajorVersion() < 3 && !IsGLExtensionEnabled("GL_EXT_sRGB"));
     ANGLE_SKIP_TEST_IF(!hasImageGLColorspaceExt());
     SourceRenderbufferTargetTextureExternalESSL3_helper(kColorspaceAttribs);
 }